Sleeping well is essential for our health, mood, and performance. But what happens when we leave Earth and venture into space, where the environment is vastly different from what we are used to? How do astronauts cope with the challenges of sleeping in orbit and on other planets?
This is not a hypothetical question. For nearly 23 years, rotating crews have been living and working aboard the International Space Station (ISS), spending an average of six months in microgravity. And in the near future, NASA plans to send humans back to the moon and eventually to Mars, where they will face even more difficulties in getting a good night’s rest.
One of the main challenges for astronauts is their sleep environment. On the ISS, they sleep in crew quarters that are about the size of a phone booth, with limited privacy and noise insulation. They also have to deal with the effects of zero gravity, which can cause them to float away from their sleeping bags or bump into walls and equipment.
On future missions to the moon and Mars, astronauts will sleep in even smaller spaces, such as the Orion capsule or a lunar habitat. “I think of it like camping,” said Dr. Erin Flynn-Evans, director of the Fatigue Countermeasures Laboratory at NASA’s Ames Research Center. “If it’s for a couple days, probably no big deal. But the longer you’re in close quarters with someone, the more disruptive that can be.”
Another challenge is the disruption of the circadian rhythm, the body’s natural clock that regulates sleeping and waking cycles. On Earth, this clock is synchronized by the exposure to natural light and darkness. But in space, this cue is lost or distorted.
On the ISS, astronauts experience 16 sunrises and sunsets a day, which can confuse their biological clocks and make them feel jet-lagged. On Mars, the day-night cycle is 24 hours and 39 minutes long, which means that astronauts will have to adjust their schedules by 39 minutes every day.
“Light is what resets our circadian rhythm and keeps us organized to that day-night cycle, but in space we have several challenges,” Flynn-Evans said.
To help astronauts sleep better in space, NASA has developed several countermeasures and technologies. One of them is the use of LED lights on the ISS that can change color and brightness to mimic natural light on Earth. These lights can also be programmed to shift gradually from blue to red hues, which can promote relaxation and sleepiness.
Another countermeasure is the use of medication. Astronauts can take melatonin, a hormone that regulates sleep, or zolpidem, a sedative that induces sleep. However, these drugs are not without side effects, such as drowsiness or dependency.
A third countermeasure is the use of behavioral interventions, such as education, training, and feedback. Astronauts can learn about the importance of sleep hygiene, such as avoiding caffeine or bright screens before bedtime. They can also monitor their sleep patterns and performance using wearable devices and software tools.
“We’re trying to figure out how to optimize sleep for astronauts so that they can be as productive and healthy as possible,” said Dr. Daniel Mollicone, CEO and chief scientist of Pulsar Informatics, a company that develops fatigue risk management systems for NASA and other clients.
Sleeping well in space is not only a matter of comfort but also of safety. Research has shown that sleep deprivation can impair cognitive functions such as memory, attention, reaction time, and decision making.
“We have a lot of data that shows that when people are sleep deprived, they make more errors, they have slower reaction times, they have impaired memory,” said Dr. Laura Barger, associate professor of medicine at Harvard Medical School and senior research scientist at Brigham and Women’s Hospital.
This can have serious consequences for astronauts who have to perform complex tasks such as operating machinery, conducting experiments, or performing extravehicular activities (EVAs).
“It’s like a perpetual jet lag,” said Dr. Mathias Basner, professor of psychiatry at the University of Pennsylvania and principal investigator of the NASA-funded Individualized Behavioral Intervention for Sleep and Performance During Spaceflight study.
As humans explore deeper into space, sleeping well will become even more crucial for their well-being and success. By understanding the challenges and solutions for sleeping in space, we can ensure that astronauts will be ready to face the wonders and dangers of the final frontier.