The science of sleep in space

Sarah Al-Ahmed: How do astronauts sleep in space? And what happens when they can't? We'll find out this week on Planetary Radio.

I'm Sarah Al-Ahmed of The Planetary Society with more of the human adventure across our solar system and beyond. Today we're joined by Erin Flynn-Evans, director of the Fatigue Countermeasures Laboratory at NASA Ames Research Center. She'll take us inside the world of sleeping in space to share how we measure it, why it matters, and what we're still learning as we prepare for long-term duration missions to the moon and Mars.

Then we'll get a quick space policy update with Casey Dreier, the chief of Space Policy at The Planetary Society, and Jack Kiraly, our director of Government Relations. They'll help impact new developments in NASA's budget and what that means for the agency's science goals.

And later, Bruce Betts, our chief scientist, joins us for a sleepy edition of What's Up, where we talk about the times that robotic spacecraft go into safe mode or low-power standby during their journeys.

If you love Planetary radio and want to stay informed about the latest space discoveries, make sure you hit the subscribe button on your favorite podcasting platform. By subscribing, you'll never miss an episode filled with new and awe-inspiring ways to know the cosmos and our place within it.

We talk a lot on this show about planetary geology, spacecraft, and missions that can show us the worlds beyond our own, but none of that is possible without humans who are rested and ready to respond when it counts. Our guest today, Dr. Erin Flynn-Evans, is the director of the Fatigue Countermeasures Laboratory at NASA Ames Research Center in Mountain View, California. Her team studies sleep alertness and performance in high-stakes environments, especially in space. Her work helps ensure that crews stay healthy and mission-ready for managing circadian rhythms on the International Space Station, to laying the groundwork for future crewed missions beyond Earth.

But Erin didn't always know that she was going to end up working at NASA. She started her academic journey in music and psychology and then later discovered sleep studies while working as a sleep technician at Brigham and Women's Hospital in Boston, Massachusetts. That early hands-on experience ultimately led her to her passion for sleep science and a career at NASA. Erin joined me to talk about how astronauts sleep in microgravity and what happens when they don't get enough rest, which as it turns out is pretty frequent. She'll also share some of the surprising ways that studying sleep in space is helping humans get more rest down here on the ground.

Hey Erin, thanks for joining me.

Erin Flynn-Evans: Hi. Thanks for having me.

Sarah Al-Ahmed: So you began your career in music and psychology before you transitioned into sleep studies. What experiences led you toward this career instead?

Erin Flynn-Evans: So I grew up in a farm and didn't really have a lot of direction coming out of high school and going into college, and so I enjoyed music, thought psychology was interesting, and put the two together thinking that I would go off on a career in music therapy. And then like many young people realized, I didn't like it at all after I started to do it a little bit and I had done a senior thesis in my psychology courses on sleep and I thought, "Well, that was kind of interesting." And so I applied to work in a sleep lab, read a lot of books about sleep, got really excited because it's a fairly young field. There's still so much discovery that happens with sleep every day. And so that's what really drew me to sleep and circadian science as a career path.

Sarah Al-Ahmed: And along that vein, what do you think are some of the biggest questions or frontiers in this field that are really driving the field forward?

Erin Flynn-Evans: Well, the cool thing about sleep and circadian science is that it really touches every body system. When I have interns in my lab now, I always tell them you can put sleep and anything together. So if you're interested in immune function, sleep touches that. If you're interested in, I don't know, economics, you can find a way to connect sleep to that.

And so when it comes to the next frontier, I sort of see two areas. One, as we understand the wiring of the circadian system in the brain, it would be really cool if we could develop new tools to make people shift faster, say, when traveling across time zones sort of solve the jet lag problem. I think that that will happen sometime, maybe not in our lifetimes, but sometime in the future.

And I think the other sort of more near term interesting horizon is the interactions between sleep and metabolism. So of course we have a lot of interesting influencers out there purporting like fasting and things like that, but there is some science to connect circadian rhythms and sleep to meal timing and metabolism. And I think that that's an area that is really becoming very interesting, that as we get more science to support how those two major body systems work together, we may be able to make really big leaps in how we help people both eat well and also sleep well and then combine the two to sort of have targeted countermeasures for people in different situations.

Sarah Al-Ahmed: Yeah, I mean it's a very useful thing. Even I'm trying to make sure I do no late night snacking, so I don't have weird dreams, that kind of thing.

Erin Flynn-Evans: Yeah.

Sarah Al-Ahmed: But before you began working at NASA Ames, you did sleep fatigue research on police officers and doctors and even some astronauts. What were the most useful aspects of that early research that you can now apply to what you're doing at NASA?

Erin Flynn-Evans: Yeah, I think the cool thing about what I do at NASA is it does really apply to lots of different populations on the ground. And so the early experiences that I had working with high performing physicians, police officers, firefighters, people in occupational settings who maybe aren't able to get the sleep that they need on a regular basis but also have to perform at a very high level, really helped inform the work that we do at NASA because of course in those populations, making a mistake is going to potentially have pretty high consequences. The same is true in space.

And so we did a number of things with police officers and with physicians to adjust their schedules to make it so that they were able to sort of maximize their rest and maximize their performance when they were working. We also provided them with different types of countermeasures, like changes in their lighting or strategic use of caffeine or timing about when to nap so that they would be able to perform at their best on their job. And we do the exact same thing with astronaut populations.

Sarah Al-Ahmed: Yeah, those are good groups of people to study. I have a lot of people who are physicians in my family. The amount of lack of sleep they get and the way that they can impact their lives is just, oh, people need to get their sleep. It's so important.

But now you lead the Fatigue Countermeasures Laboratory at NASA Ames Research Center. What kinds of things does the lab study and how do those results impact the lives of astronauts and space travelers and people that work in space fields?

Erin Flynn-Evans: So we are actually running a study as we speak. And what we're studying right now is how the impact of the spaceflight vehicles that we'll take to the moon and beyond impact sleep. So we bring people into the lab and we play the audio recordings from the Artemis I mission while they sleep. It's really loud. It's like 67 decibels. It's like having a hairdryer on while you're sleeping. It surrounds them. It's not like this nice gentle white noise. It is a very obtrusive sound. And then there are a lot of other random sounds that come into it as the space vehicle moves. And of course you can imagine sleeping with a hairdryer and lots of random knocking in a strange place might make it difficult to sleep.

And so by studying people in this laboratory environment where we've simulated the conditions of spaceflight, we should be able to develop tools and techniques that we can use to help the astronauts when we actually do go to the moon for Artemis II and beyond.

And then when we think about bringing that back to Earth, there are a lot of people who have to sleep in strange and noisy environments. The very obvious immediate group, our military populations, people sleeping on an aircraft carrier are going to be hearing random noises as different missions are deploying. But the same can be true for people who, say, are working on an oil rig for a couple of weeks at a time where they may have to sleep in shifts and the environment may be quite noisy. Or even in a hospital environment. There have been a number of studies that have shown that even patients in the hospital have disrupted sleep due to all of the noises that are happening in their room from all of the machines that people are hooked up to. And so by learning about how people attend to noise during sleep, we should be able to develop tools that not only can help our astronauts sleep well and perform well, but can also help people here on Earth.

Sarah Al-Ahmed: How do you actually go about studying the sleeping patterns of people while they're in space? Is it a situation where you get the data back afterwards or you do mostly analog studies or do we hook up some kind of sensors to people when they're on the ISS?

Erin Flynn-Evans: Well, we do all kinds of things while our astronauts are in space. So the most common way that we study them is to use activity monitors. These are pretty similar to the fitness trackers that everyone is wearing these days. We have research-grade devices that we have on the astronauts while they're in space. And we get that data after they return so we can see how their sleep changes from the time that they're on Earth, before they go to space, to their time in space, to their time after they come back. But of course, that only gives us kind of basic information about sleep.

The way that we would really like to study sleep all the time is by using EEG or these sensors on the head that can tell us about the astronauts' brain waves. There are not very many opportunities for us to do that because every ounce of payload that we've sent to space is very expensive, and this equipment is kind of big and bulky. It also takes special training to be able to apply it. So we have a few cases throughout the history of spaceflight where we've been able to collect that EEG data, but that's not our norm. Typically, we do that in the lab so that we can really investigate sleep deeply. But when we go into the field or into space, we're typically using these activity monitors.

Sarah Al-Ahmed: Are you usually studying people who are US astronauts or is there some kind of international collaboration on sleep studies between different space agencies?

Erin Flynn-Evans: Well, since we have the International Space Station, we do have a lot of collaborations. Any astronaut can volunteer to be part of our studies. And so we do follow pretty standard ethics procedures between NASA and the European Space Agency in particular. And our protocols are all reviewed by multiple agencies around the world. And if an astronaut is going to space and they're from a different country and they think that the study that we're doing is interesting, then yes, they can absolutely volunteer to participate and we would be able to include their data in our analysis.

Sarah Al-Ahmed: So what is the typical sleep environment like on the International Space Station?

Erin Flynn-Evans: Well, the space station is probably the best of the best when it comes to spaceflight sleep. We've come a long way since the early days of sleeping in space. And the astronauts on the space station each have what we call private crew quarters. And so they're like little telephone booth that the astronauts can go into. It's kind of like little bedroom for them. They can store some of their belongings there. They can set up their computer or iPad so that they can watch a movie or make a call in this private space. And of course they have a sleeping bag that they can hook to the wall. And by shutting the doors while they sleep, they have really nice privacy. The air temperature is pretty good by all accounts. And it's quiet. So the astronauts sleeping on the space station typically report that they enjoy that sleeping environment.

Sarah Al-Ahmed: As you mentioned, I mean the sleep challenges aboard the ISS are very different from what you'll experience if you're on a shorter term flight or say you're going on one of the Artemis missions for a few weeks. What are some of the unique challenges in these different kinds of sleep environments and space?

Erin Flynn-Evans: It's going to be incredibly different from what we experience on the space station. So the space station is a really well-oiled machine, literally. We've refined the way that we work and live on the space station over many, many years. When we go on our Artemis II mission, for example, we'll have the Orion spacecraft. And the size of that vehicle is so much smaller than the space station. The space station is the size of a US football field. Orion is the size of someone's office. And four astronauts have to live there, work there, and sleep there. And so they're not going to have private sleep stations. They're going to have to just have sleeping bags and tether themselves to the wall or sort of sleep in hammocks. So that will induce some difficulty. I think of it kind of like going on a camping trip for a couple of weeks. You can tolerate the people around you for short term, but it may be difficult the longer they're in space.

And then there are going to be a number of scheduling challenges as well, because the way orbital dynamics work when we're going to the moon, we have to move that vehicle at different times, which means that the astronauts will have to be awake at different times of day and night in order to move the vehicle towards the trajectory of the moon. And so that means we can't have this perfect sleep schedule. Their sleep will probably have to shift around quite a bit, and that means that we have to support them by providing them with tools to be able to sleep during their biological day and maybe be awake during their biological night.

Sarah Al-Ahmed: That's got to be so challenging. I mean, even I, I travel just a little bit, go to Washington, DC or something and suddenly my sleep is completely off. I can't even imagine having something like that happen.

But you said this as well, some people prefer to tether their sleeping bags to the walls and other people kind of like free-floating. How do the differences in the way that people enjoy sleeping in space change the way we design these habitats?

Erin Flynn-Evans: So if we have the opportunity to design a habitat specifically for sleep, I think that the model that we have on the space station is great. Again, telephone booth sized sleeping quarters. So someone who really likes that sensation of free-floating will be able to just kind of let themselves go because if they're in a confined space, they can bounce around a little bit and they're not going to bump into any important equipment probably. But of course if you tried to do that in a smaller vehicle or if you just tried to free float in the main quarters of the space station, you could run into things.

There are some old anecdotes from the space station Mir where people did sleep in the common areas and would just float by as other astronauts were working. So I can't imagine what that was like. But of course, I don't think most astronauts would want to sleep like that. Those who like free floating, I think, would prefer to be in sort of the confined quarters of a safe space.

Sarah Al-Ahmed: It's one of the funniest zero-G indicators I've ever heard of. It's just your friend floating down a hallway. But we need to make these design choices about these habitats in order to make sure that people can sleep effectively. And you've said on the ISS that people have these nice little enclosures, but how much control do they have over things like lighting and airflow or even white noise?

Erin Flynn-Evans: So the sleep stations are pretty good when it comes to the environmental conditions to support sleep. They don't have a whole lot of control over the temperature, so that's relatively fixed. But they can insulate themselves by putting on additional layers.

One astronaut reported to me that she would put a computer by her feet before going to bed to warm herself up. So you may have differences in preference for temperature level during sleep, and the astronauts get creative in the way they solve those problems.

When it comes to airflow, there are little knobs that can be turned to increase or decrease the airflow, but of course on the space station, we have to think about things that we don't have to think about here on Earth. You can't turn the airflow completely off because we expire CO2, and that CO2 can just sort of sit in front of your face. And so we want to maintain some sort of airflow through the sleep station to avoid an increased buildup of a pocket of CO2 in the sleep area. So again, little details that will come into the design of future spacecraft that we sort of solved on the space station but may not be perfect for every single person who goes up there.

And then when it comes to lighting, we have specialized lights in the crew quarters. They start from a relatively blue wavelength in the morning and they shift to a relatively red wavelength in the evening, and that's to sort of mimic the type of solar cycle that we experience here on Earth. But the astronauts can adjust it so if it's too bright for them, they can turn it down so that they can prepare for sleep better, or turn it entirely off of course during the night and have a really blacked out sleep environment.

Sarah Al-Ahmed: But even with all of those accommodations, astronauts tend to sleep maybe about six hours on average, at least from what I've read. And that's several hours off from about eight or eight and a half hours they're usually allotted to take their sleep time. What do you think are the biggest contributors to this kind of chronic sleep loss?

Erin Flynn-Evans: That's a great question. And we've been working on that for many years and really trying to crack it. I think one of the biggest contributors historically has been circadian misalignment. So circadian misalignment is essentially the same thing that shift workers on Earth experience. When you're trying to work against your body clock, stay up all night to complete a shift and then sleep during the day, your circadian system is really trying to keep you awake during the day and asleep at night. And when you try to oppose that system, you have difficulty as anyone who's stayed awake all night knows. And that circadian misalignment comes in large part from the way that we've scheduled astronauts historically.

And so I would say scheduling for space is really hard. There are a lot of activities that planners have to fit in at different times of day. Visiting vehicles will come up to the space station at all different times of day and night. And the way that we've historically had the astronauts adjust to their schedule is just really not taking sleep into account very well at all. The astronauts might shift their sleep from effectively a Greenwich Mean Time night, which is the main timing that we use on the space station, to sleeping during the middle of the day and then switching back after just a couple of days. Or they might just progressively shift later and later and later and later over the course of two weeks.

But just these examples that I'm giving can really probably show you that it's not been a very sleep-friendly environment. It's sort of like jet lag on steroids. We've tried very hard in recent years to keep the astronauts scheduled to just that very standard Greenwich Mean Time schedule and only shifting them when it's absolutely necessary. And we are starting to see improvements in their sleep. So I think that's probably one of the big factors. There may be effects of space flight itself, microgravity, radiation, but we really can't tell at this point whether those factors come into play.

Sarah Al-Ahmed: Even so, I imagine that 90 minute light dark cycle aboard the ISS is going to do some very strange things to your circadian rhythm.

Erin Flynn-Evans: It absolutely can. So as you said, unlike here on Earth where we don't really have to think about our circadian rhythm if we are trying to be awake during the day and sleep at night, we just live on the surface of this planet, the Earth turns and at night we get the drive to sleep, and during the day we have the strive to be awake because light is what tells our circadian rhythm when we should be awake and sleep.

But the space station goes around the Earth every 90 minutes. So there's about a 45-minute light, a 45 minute dark cycle. And because of that, if the astronauts, say, go look out the window right before they go to bed, they'll be exposed to light that's about 20% brighter than what they would experience on the surface of the Earth, and that's going to really shift their circadian rhythm to a later phase. I think a lot of people probably here on Earth have heard you shouldn't be looking at screens right before you go to bed. Well, this is orders of magnitude greater than that issue. If you're looking at bright sunlight right before you go to bed, that will shift your circadian rhythm. And so we try to let the astronauts know that it's important that they try to shield themselves from those bright light exposures in order to maintain circadian alignment.

Sarah Al-Ahmed: But even when they're actually sleeping, does space impact the sleep cycle itself, like the amount of random eye movement they get or anything like that?

Erin Flynn-Evans: There have been studies that suggest that there are changes in eye movements specifically when astronauts go to space, but these have been very, very small studies that haven't yet been replicated. And so I want to be very cautious in making big claims about that. In some of the work that my team has done with collaborators at ESA, we've also found that there are changes in the microstructure of sleep during space flight.

So for example, we have these sleep spindles during our sleep, which are just these fast frequency little bursts of activity that seem to be associated with motor skill learning. And when astronauts go to space, we see increases in these sleep spindles. That might be because there's a big motor skill learning that happens when you go from Earth to space. You use your legs a lot less and you use your arms a lot more to get around.

Now, can't say anything causal yet. This is preliminary data, but it is really exciting to think about how sleep may be facilitating adaptation to space flight and helping us learn to kind of live in this different type of environment.

Sarah Al-Ahmed: Do people kind of acclimate to this situation over time or is this just a pervasive issue?

Erin Flynn-Evans: It's difficult to say how things may change over time. Most of the studies that we have looking at brain activity during sleep in space is limited to just a few days. We do have a study from the space station Mir that showed that there were changes in REM sleep, so rapid eye movement sleep, and non REM sleep, which would be like your deeper sleep over the course of time and space, where REM sleep seems to be reduced and then maybe recover.

But it's really hard to know if we can attribute that to space flight or if that's just an effect of the way that the astronauts were scheduled. We see the same types of things in chronic sleep deprivation here on Earth. So it's possible that the astronauts were just a bit sleep-deprived when they first were in space, and then over time there was a reorganization of their sleep system. But right now we don't have enough of this EEG data, this brain activity data to really say for sure.

Sarah Al-Ahmed: Have we ever observed people in space who were in simulations having issues and reaction time or anything because of the lack of sleep?

Erin Flynn-Evans: We have. So there are a couple of examples that I can point to you. So first, researchers at the University of Pennsylvania, Dr. Mathias Basner, Dr. David Dinges, Dr. Chris Jones, recently published a study showing that reaction time is slower with really reduced hours of sleep. So for every hour less sleep you get, you have worse reaction time.

The astronauts are high performers though. So if you look at the reaction time, it's not that bad. And if anyone on Earth were to take a reaction time test, their performance would be quite similar to an astronaut who's affected by sleep loss. So we're not talking about huge deficits in performance.

But we do worry about these things because there was an incident on the space station Mir many years ago where one of the cosmonauts reportedly had a very difficult night of sleep, was controlling the robotic arm, which is a very complex maneuver on the space station. It's this little arm that reaches out and will grab resupply vessels and bring them in. It represents one of the more complicated and potentially dangerous activities the astronauts do. And after this cosmonaut had a difficult night of sleep and had some equipment failures, he wasn't able to effectively reach out and grab a progress resupply vessel as it came and it actually hit the space station. And so that's really an example of how extreme sleep loss could have a huge and negative impact on life in space. We all make little mistakes from time to time. We attribute them sometimes to sleep loss. But when you're in space, the stakes are a lot higher.

Sarah Al-Ahmed: So how do astronauts actually deal with the exhaustion of this? I mean, clearly there are high performers that are going to try to do their best, but there's got to be something you can do to try to mitigate it, like take naps or something.

Erin Flynn-Evans: Absolutely. We pull out all the stops. And so firstly, of course, the astronauts are all engaged with their flight surgeons or flight doctors all the time. And so if someone isn't feeling particularly at their best, they'll work with their flight surgeon to figure out a plan to get them back on track. And that might mean that they're taking a nap. It might mean that they just get a little extra time off to have a longer sleep. It might mean that their physician tells them they should take a medication or maybe use some caffeine to help them get into an alertness mode. So that's really the main line of defense that we take.

But of course there are other things too. We try to build mitigations into the operation. So for example, as I mentioned before, we try to really keep their sleep as stable as possible so that we're not shifting them around all over the place, so that they can start with a really nice rested baseline.

We also, as I mentioned, have these lights, specialized lights on the space station. And when you're under a brighter and bluer light, you're going to feel more alert. And so by having those lights on the space station, we hope that that just gives them a general alertness boost. And that's also something that people on Earth can use. If you're ever feeling a little down, going for a walk outside does more than just give you a sort of refreshed break, that light will enhance your alertness and performance going forward.

Sarah Al-Ahmed: One more reason to take your mental health walks.

Erin Flynn-Evans: Absolutely.

Sarah Al-Ahmed: But also maybe get some kind of program on your laptop or your phone that helps you filter out blue light as you get nearer to sleep times. There's all kinds of ways that this can apply to our lives here on Earth, but so important to make sure that our astronauts are getting the sleep that they need.

You did mention that some people take sleep medications or maybe extra caffeine in order to be awake while they're doing things in space. Have we done any studies specifically on how these substances impact people in microgravity?

Erin Flynn-Evans: We have. And so when it comes to hypnotic medication, which are sleep medications, we find that the astronauts don't really seem to benefit a whole lot from them. They fall asleep a little bit faster, about 10 minutes faster. But their sleep duration doesn't really change. Their reported sleep quality doesn't really change either. And so we're not sure that the way that medications work in space is the same as the way that they work on Earth.

On Earth, we have lots of protections for our medications so that they don't degrade very quickly. But in space, we have all kinds of hazards like radiation that could actually be affecting the medications that the astronauts have access to. So that's one thing.

When it comes to caffeine, we actually do find that most astronauts use caffeine probably just like the rest of us do, maybe in order to fight off that grogginess, which is called sleep inertia, which we all feel in the morning as we wake up. They tend to have about a cup of coffee a day on average. And that also does seem to have a positive impact on their alertness and performance.

Sarah Al-Ahmed: Do you also take the sleep inertia into account when making schedules for astronaut sleep?

Erin Flynn-Evans: So we try to. So sleep inertia can be so severe at times that it's worse than staying awake for 24 hours. So that is if you're waking up from deep sleep, so you say you've taken a nap, I'm sure many people have probably been in this situation where you've taken a nap and you wake up and you sort of feel worse than you did before you took the nap in the first place, in those situations, you're probably waking up from deep sleep.

And in my lab, we have an expert on sleep inertia, Dr. Cassie Hilditch. And she's done a ton of work looking at how sleep inertia manifests and how we can help mitigate some of the impacts of sleep inertia. One of the things that we recommend is that people don't engage in activities that are mentally demanding for about 20 minutes to let that sleep inertia kind of burn off. But then we can also provide countermeasures like bright light and caffeine because those also help reduce the burden of sleep inertia.

Sarah Al-Ahmed: We'll be right back with the rest of my interview with Erin Flynn-Evans after the short break.

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Sarah Al-Ahmed: Well, when we're talking about people working in space-related fields, it's not just the people that are actually in space that have to deal with sleep fatigue because of these things. A big example I'm thinking of are the people that work on Mars time in order to coordinate with Mars rovers and things like that. How does that impact people on Earth? Even though they're not working in space, they might still experience these issues with fatigue.

Erin Flynn-Evans: It's a really cool phenomenon that we use to send these rovers to Mars. I think many people on Earth probably don't even realize this is happening. But many of the scientists and engineers who work on our Mars rovers and landers will adopt Mars time. Mars time is 24 hours and 39 minutes. And so if you think about that, I always say Mars rotates at a point that is close to Earth, but just far enough that some people can have significant difficulty adapting because you're going to bed 39 minutes later each day. And so for the first couple of days, that probably wouldn't be a big deal. But over time, that's going to accumulate. And essentially you're going to start sleeping during the morning, then the midday, then the afternoon, then you'll cycle back to the Earth night. And so when you're trying to do this while also living on Earth and not only doing your work but juggling family activities, it can be quite difficult.

I was fortunate to be able to visit JPL several times and work with people down there who have had to work on these schedules. And I also worked with Dr. Laura Barger on the Phoenix Mars Lander project. For the first 10 weeks of that mission, scientists and engineers adopted that Mars schedule. And we were able to help them adjust by giving them fatigue management training. So blocking out their windows. They weren't getting that bright Earth sun when they were trying to sleep during the day. And then also providing them with blue light boxes to put at their workstations to help them shift to Mars time.

Sarah Al-Ahmed: Are there any situations where most of the team is okay adapting to this Mars time, but there are just certain people on the team that just can't deal with the changing sleep? How do you adapt a situation like that?

Erin Flynn-Evans: It can be very difficult for some people's circadian rhythms to adapt to a 24 hour and 39 minute day length because the average human circadian period is 24 hours and 12 minutes. And so you might be thinking, "Well, why isn't it 24?" Our circadian rhythm is intended to be flexible so that we can adapt to seasons. Obviously that helps us when we adapt to jet lag. And 24 hours and 12 minutes is a little bit off, that 24 hours and 39 minutes.

There are also people who have shorter than 24 hour circadian periods, so these would be early types. So somebody who wakes up early in the morning and is just chipper and ready to go without an alarm clock would probably have a lot of difficulty adapting to Mars time. And we did find that a few people weren't able to adjust very easily even with the countermeasures that we put in place. And so for those people, what we'll probably need to do going forward, especially as we actually go to Mars, is provide other countermeasures for them. So maybe somebody who has a short circadian period, maybe they'll need to take a nap every day in order to be able to have the stamina to stay up that extra 39 minutes into the evening each day. We don't have that exactly worked out yet, but that's definitely something that we need to work on before we actually go to the red planet.

Sarah Al-Ahmed: How do analog environments like the studies that we've been doing on people in Antarctica or other closed environments help us understand sleep and space better?

Erin Flynn-Evans: Yeah. So it's really cool to be able to do fake space missions. So we have habitats at Johnson Space Center where we have people live and work together for long periods of time, just like on a space mission, we have a mission control that works with them. Those studies are my favorite because we can create a space-like environment, but we can manipulate the variables that the people are exposed to and collect a whole lot more data.

So several years ago we did a study in the Human Exploration Research Analog at Johnson Space Center where we had people confined to the habitat, four people at a time, for 45 days and they only got five hours of sleep during the week and eight hours on weekends. And during that mission, we were able to look at how well they performed, but also how well they interacted, how their mood changed. You can imagine this could put a lot of stress on a team of people trying to work effectively together. And we would never do that to our astronauts in space, but by studying these people in these habitats, we're able to learn a lot more.

Antarctica represents a different type of environment because of course in Antarctica we have either constant light or constant dark or very long periods of light and dark. And I think Antarctica is going to be a really cool analog for us when we go to the moon because when we go to the south pole of the moon, we will have near constant light for 28 days or so while we're operating there. And we haven't really been in an environment where we've had near constant light for our astronauts, Again, when we go around the Earth in low Earth orbit on the space station or previously on our other space vehicles, we have that 90-minute light dark cycle. When we go to Mars, we'll still have the rotation of a planet. But when we go to the moon, we're just going to have surface operations under this constant light environment. So I think we need to do a lot more work in our Antarctic analogs with the people who are living and working there to better understand how that lighting environment will affect our astronauts when they go to the moon.

Sarah Al-Ahmed: Do you think there's anything that we've learned from studying people sleeping in space that has made life better for people here on Earth?

Erin Flynn-Evans: Absolutely. I mean, I think lighting is probably the biggest thing that we've come to understand better through studies that NASA has funded over the years. We now know that blue wavelengths of light have the strongest impact on the circadian system. And so most people don't want to or need to sit under a bright blue light. In fact, we've had complaints from people in the early days of doing experiments that you kind of look like a smurf and you don't really like the way that you look under a blue light. But we can now create these spectrally tuned lights that just have, we call them blue-enriched. So they have more blue in the overall spectrum. So they're visibly white. You can work under these lights, but you're also getting that really strong alerting stimulus.

Lots of researchers now have taken these concepts and brought these blue-enriched lights into environments like hospitals or care homes. Having blue-enriched lights in care homes actually reduces fall risk among elderly people. So lots of really cool uses for this type of lighting that we've studied for spaceflight that go beyond just your traditional shift work or jet lag here on Earth.

Sarah Al-Ahmed: What do you see as the top research priorities in sleep and circadian science as we go into the future of missions beyond Earth orbit?

Erin Flynn-Evans: Wow. Well, I mean we really have to understand what the limitations are to adapting to the Mars' soul. So we've done a few studies as we discussed on people are working on our Mars robotic missions, but we really need to get this right when we send people to Mars. Because if a human can't adapt to that day length, it's going to feel like perpetual jet lag. And nobody likes the feeling of jet lag. Imagine trying to work your best if you're just constantly traveling around the world, it's really hard to do. So we need to make sure that we have tools that astronauts will be able to use to be able to perform well and get the sleep that they need to support their activities when we go to Mars. I would say that's number one.

But beyond that, I think that we should look more into shallow metabolic depression like torpor hibernation, the realm of science fiction. If we want to explore beyond our solar system, we need tools like maybe based in anesthesia that can allow people to just go into a low metabolic state so we don't have to use as many supplies as we go on that mission because of course we're going to be volume limited by the space vehicle that we take on an extended duration mission. So I think we should be looking into things like that, even though it may sound a little strange to some people.

And then coming back to the nearer term activities, there's just so many things that we don't understand just about brain function during spaceflight. There's a fluid shift that happens during space flight. So instead of having gravity pull all of the fluids down, fluids redistribute through the body. We have this thing called the glymphatic system, which clears waste products, dirt, in the brain while we sleep. We don't understand at all how these fluid shifts may interact with the way that our brain does normal processing. So I think we need a lot more basic science as well before we send people too far away.

Sarah Al-Ahmed: Well, this is the kind of science that really remembers that we're all human. And as much as we want to go to space, we got to make sure that we're doing it in a way that respects what we need to be our best. So I'm really glad that people like you are doing this kind of research.

Erin Flynn-Evans: Thank you so much. I love my job.

Sarah Al-Ahmed: Well, thanks for joining us, Erin. And good luck in the future. We're going to need this kind of study if we're going to be sending humans to the moon and beyond and to Mars.

Erin Flynn-Evans: Thank you so much for your interest.

Sarah Al-Ahmed: And now it's time for a quick Space Policy Update with Casey Dreier, The Planetary Society's chief of Space Policy, and Jack Kiraly, our director of government relations. This week, they break down the latest developments in NASA's budget negotiations and what that means for the future of space science.

Casey Dreier: All right, I'm here with my colleague, Jack Kiraly, delighted to be here, to talk to all of you about the current updates in space policy. There's a lot happening as most of you know. And we have some, Jack, unusually positive news to share with folks.

Jack Kiraly: Indeed we do. So Congress has, as of this episode coming out, will be preparing for their August recess, having had a pretty productive July session of the legislative body. And both the House and Senate have produced budget proposals for NASA that wholly reject the cuts proposed by the Office of Management and Budget. Not giving a little inch here and there. It is a total rejection.

Casey Dreier: Yeah, 24.9 billion for NASA for each House and Senate. That's the same as 2025.

Jack Kiraly: Yep. Basically flat funding, no cuts as proposed by the administration. The House number is a little bit weaker on science, but it's still that overall top line number that's really important here because that is clearly showing congressional intent when it comes to the future of the NASA budget and the future of American leadership in space exploration. Both chambers, though they don't agree on much some days, have agreed that we need to keep NASA whole in fiscal year 2026, which starts just a few months from now in October 1st.

Casey Dreier: And it's worth emphasizing the House number for science represents an 18% cut at $6 billion, but I guess this is how low our bar is. That's way better than a 47% cut. I mean substantially better. And it is not equally distributed, unfortunately, primarily falls on Earth science for I'd say generally political reasons. But there is, again, the Senate number itself, full, flat, straightforward funding. No cuts for NASA science anywhere.

And I would say even the kind of astonishing thing in the Senate budget is that most of the projects and missions that are identified for cancellation in the White House OMB budget request actually would see budget increases under the Senate number. That's a pretty clear signal about how Congress, and again, Republican Congress, this is the president's own party that is controlling these chambers, how they're reacting to this proposal.

Jack Kiraly: In any normal year, this would be it.

Casey Dreier: Right.

Jack Kiraly: I mean, it is a huge victory for this movement to save NASA science, but this would be close to the end of the fight. Both chambers of Congress have announced that this is their intention. OMB's job traditionally is to look at the direction that Congress, which writes the laws and appropriates funding as delineated in Article I of the Constitution, would look at that and say, "Okay, our budget has failed." And their job between now and the actual budget passing is preparing full case would be flat funding given that both chambers have proposed that. So in a normal year, this would be close to it.

Now, unfortunately, we're not in a normal year. We're in a situation where the Office of Management Budget on a number of other agencies is working to circumvent that traditional congressional appropriations process and enact the president's budget on those agencies, in this case, starting to include NASA with calls for early termination plans for the missions they proposed to cancel like Juno, New Horizons, Cyrus Apex, and closing out of projects like Mars Sample Return and the Habitable Worlds Observatory, which again, as you know Casey, both get shout-outs in the congressional budgets. The House gives full $300 million funding, which is what it was funded at last time from our sample return. And the Senate makes huge headway on HWO, the Habitable Worlds Observatory, in allocating 150 million for that project based at the Goddard Space Flight Center, and really just began work on that in the past couple of years.

And so these things are kicking up into a higher gear, and Congress is behind them. And as you pointed out, the missions that are currently healthy, currently producing science, allowing scientists in the US to lead the world in scientific discovery and exploration, keeps those at full funding and then some in some cases.

Casey Dreier: Right. So again, we have a very aggressive, let's say, interpretation of executive authority to not spend what Congress gives. I think Russ Vought has said appropriations are a ceiling, not a floor. Obviously that's a radical interpretation. I don't think that's unfair to say. And this is going to be a major issue going forward.

So again, I think it's important, as we go forward, this is a huge, huge step that Congress has, I'd say resolutely and absolutely clearly rejected and demonstrated its intent to fund NASA at minimum at its 2024 levels, 2025 levels. And then science being a minor dispute again in that context compared to what has been proposed. So we are going to be pursuing this very closely and again, making this case that Congress has spoken, the process should be working, and that our advocates, you, or everyone who's taken action, it's working.

And to that end, Jack, we should pitch very quickly here at the end of our time. If you want to keep pressing Congress on this and keep pushing this forward, we have a bonus, bonus day of action this calendar year. Why are we doing this to ourselves, Jack? Because we care. We're doing it second time in D.C.

Jack Kiraly: And we're not just doing it by ourselves, we're doing it with friends. We have 10 partner organizations that are part of our special Day of Action on October 6th, 2025. This is an opportunity to show that space is something that brings people together across all different communities and disciplines and really is something that advances not just scientific understanding of the cosmos, but national security and national posture, economic development, technological development, and really is something that can bring people together.

So Planetary Society and 10 other organizations. Check out planetary.org/dayofaction for more information about this upcoming opportunity. And sign up to be part of this historic moment where we are going to bring together an unprecedented, we've been hearing that word a lot, an unprecedented coalition of organizations to save NASA science.

Casey Dreier: That's right. October 5th and sixth in Washington, DC. We will not be giving up on this. Thank you, Jack. Thank you listeners for letting us keep you updated.

Sarah Al-Ahmed: Now let's check in with Dr. Bruce Betts, our chief scientist for What's Up. This week, Bruce brings us a sleepy edition, exploring how and when our robotic spacecraft take breaks and go into low power mode. It's not like they need sleep, but there are situations that are kind of similar.

Hey, Bruce.

Bruce Betts: Hey, Sarah.

Sarah Al-Ahmed: I swear I didn't do this on purpose, but I know we are both rather sleepy today. And I will note for people who can't see you in real life that you're wearing a shirt that looks like the NASA logo, but says naps on it.

Bruce Betts: That's pretty cool.

Sarah Al-Ahmed: That's perfect. I could really use a nap. I don't know how astronauts do it. There are days when I am so sleepy just being here on Earth, doing my normal job. But if I do something wrong in space, it's not like I'm going to accidentally mess something up, and as we heard in the case of one of the Soviet space stations, accidentally crash a container into the side of our space station. The stuff that can happen when you're in space and you're sleepy is just so dire. So I don't know, I hope they get their caffeine in.

Bruce Betts: Don't drive sleepy. Don't drive sleepy.

Sarah Al-Ahmed: Seriously. But I mean, we've been talking about astronauts needing sleep, but I mean, what about the space robots? I know that's a kind of silly thing because they're not biological. They don't need sleep the way we do. But do spacecraft ever need to shut down or power cycle or something in order to either manage fatigue or even the environment? I don't know. Do robots need sleep?

Bruce Betts: Yes and no. That's a philosophical question. No, I don't think that... No. Strictly no, they don't, but there are things that may cause something to require, not sleep obviously, but a sleep type state. So for example, very common, very good idea when you make a spacecraft is to have a safe mode. So if it loses track of talking to Earth, it goes, "Oh no, I shouldn't use all my power. I'm going to chill, but I'm going to keep listening for Earth and talk to it once in a while. And that saves an awful lot of missions. And missions that haven't done that have paid the price.

Power issue drives it a lot. So if your robot's going around Mars and it's solar-powered and gets a bunch of dust on it, then you may not be able to drive around all during the day. You need to have some relaxed time as well as the nighttime. Where they do, if they're solar-powered, they chill pretty hard, literally and figuratively at night on Mars.

Sarah Al-Ahmed: But I mean, one more reason why robotic exploration is so awesome and actually just put them into a kind of robotic torpor almost.

Bruce Betts: You can. And you can also keep them working 24 hours a day and they don't... Well, okay, you really kind of lose the point of 24 hours a day less around Earth, but the concept being keep them working if they've got the power and the memory suppose to those silly humans.

Sarah Al-Ahmed: We also, in this episode, talked a little bit about working on Mars time. I know that you've done some Mars research, but have you ever had to exist on Mars time before?

Bruce Betts: I have not. I've been around a lot of people who were on Mars time, which can make people kind of cranky. But it is a very practical thing when especially the early, they usually do it just in the early phases after they land. There's a 40-minute difference with Earth time. So it's like changing your time zone every night by 40 minutes, but it keeps people working on the time where you've got the daylight and the communications.

Sarah Al-Ahmed: Yeah, I remember there was a while there where Casey, our chief of Space Policy, was on Mars time, but it was because-

Bruce Betts: That was just for fun.

Sarah Al-Ahmed: Well, it was because his wife was working on a Mars mission.

Bruce Betts: I'm kidding. Yes.

Sarah Al-Ahmed: Just for funsies. Just to test it. Actually, that would be an interesting thing to try. Just go for a week and see if I could do Mars time, because I am mean to myself and would do that for some reason.

Bruce Betts: There you go. Perfect.

Sarah Al-Ahmed: For science.

Bruce Betts: We look forward to hearing the result.

Sarah Al-Ahmed: I'll take notes. So on that sleepy note, what's our Random Space Fact this week?

Bruce Betts: [inaudible 00:52:23]. The Vera Rubin Observatory LSST, which recently opened in South America and is awesome, over a span of 10 years, will take pictures of more galaxies than there are people on Earth.

Sarah Al-Ahmed: Whoa.

Bruce Betts: There it is.

Sarah Al-Ahmed: That's a-

Bruce Betts: [inaudible 00:52:43] mind blown face.

Sarah Al-Ahmed: That's a lot, dude.

Bruce Betts: It's a lot of galaxies.

Sarah Al-Ahmed: It is though. There's so many people.

Bruce Betts: There's so many people. There's so many galaxies. So many more galaxies than people.

Sarah Al-Ahmed: The other day I was at a show at Griffith Observatory. And one of the people there, Laura May, who's now one of the people on All Space Considered, one of their shows, gave me a commemorative Vera Rubin quarter. So now I have one of the limited edition Vera Rubin coins, and I'm going to cherish that forever. But firs, a nap.

Bruce Betts: All right, everybody, go out there, look up the night sky and think about moisturizers for your pet naked mole rat. Thank you and good night.

Sarah Al-Ahmed: We've reached the end of this week's episode of Planetary Radio, but we'll be back next week with more space science and exploration.

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Planetary Radio is produced by The Planetary Society in Pasadena, California and is made possible by our dedicated members who stay up to watch that meteor shower even when they're sleepy. You can join us at planetary.org/join.

Mark Hilverda and Rae Paoletta are our associate producers. Casey Dreier hosts our monthly Space Policy Edition. And Matt Kaplan hosts our monthly Book Club Edition. Andrew Lucas is our audio editor.Josh Doyle composed our theme, which is arranged and performed by Pieter Schlosser. I'm Sarah Al-Ahmed, the host and producer of Planetary Radio. And until next week, I hope you get plenty of sleep. And ad astra.