Highlights

·        When astronauts orbit the Earth, it strengthens their bodies’ daily rhythms (circadian clock).
·        During space flight, sleep quality improves along with electrical heart rhythms indicating cardiovascular health, overall well-being, and anti-aging benefits.
·        Higher intensity fluctuations in Earth’s magnetism in outer space correlate with dips in nocturnal heart rate, an indicator of cardiovascular health.

Ambitious CEOs like Elon Musk and Richard Branson have touted their companies’ plans to send more people to space. But what about space travel-related health risks for the brave people who will pay these companies to exit Earth’s stratosphere? After all, humans have evolved with and adapted to Earth’s ground level gravity and atmospheric conditions. So, it’s intuitive to think that maybe the environmental alterations from entering space would have toxic effects. But what if, contrary to these notions, space travel has anti-aging benefits?

Otsuka and colleagues from the Japan Aerospace Exploration Agency showed in a Scientific Reports publication that long-term space missions improve astronauts’ sleep quality while in space and provide anti-aging cardiovascular benefits. The Japanese research team linked the anti-aging benefits with increased heart rate variability — where durations between heartbeats fluctuate — an indicator of relaxation and overall health. They also found that time in space reduces nighttime heart rate, indicative of good cardiovascular health. These findings suggest space travel supports positive health and possible anti-aging benefits.

“The most striking result of this investigation is the larger prominence of the circadian [heart rate] rhythm in space in ten astronauts living on the [International Space Station] for about 6 months, an indication that long-duration spaceflight may have slowed down aging,” said Otsuka and colleagues.

Space Travel’s Effects on Aging

Previous research had presented conflicting reports about space travel’s effects on health and aging. On the one hand, studies have indicated that space travel promotes extension of chromosomal ends (telomeres), an indicator of cell aging reversal. More evidence supporting that space travel can backpedal age comes from research that shows time in space reverses DNA marker signatures of aging called methylation patterns. On the other hand, some studies have shown that space travel can interfere with the body’s natural clock (circadian rhythm) to alter sleep patterns and drive negative health and aging consequences.

Since some of the data suggests that spending time in space can benefit aging, Otsuka and colleagues decided to look at the negative impacts in more detail. The research team wanted to know whether altered sleeping patterns in space do in fact contribute to disease. So, they measured cardiovascular electrical waves and sleep quality as health indicators in 10 astronauts that spent about six months in space.

Nocturnal Heart Rates Dip in Space

Otsuka and colleagues measured sleep quality by looking at the circadian amplitude, the dip in heart rate during the night. They found a more robust dip in nighttime heart rate during two segments of the space mission compared to before and after the space flight. Since sleep quality deteriorates with aging along with a blunted nocturnal heart rate dip, Otsuka and colleagues interpreted this as aging reversal.

(Otsuka et al., 2021 | Scientific Reports) Spending time in space increases the difference between daytime and nighttime heart rate, an indicator of cardiovascular health. The dip in nighttime heart rate, the cardiac amplitude of heart rate, significantly increased at two time points during space travel (ISS01 and ISS02) compared to before space flight (Before) and after return to Earth (After).


Better Sleep in Space

Otsuka and colleagues used actigraphy — the use of a watch-like sensor to measure physical activity — and heart monitoring to measure sleep patterns. All of the astronauts had better sleep patterns with less insomnia in space compared to these measurements on Earth. Their findings indicate that better sleep without interruptions or insomnia happens during extensive space flight missions.

(Otsuka et al., 2021 | Scientific Reports) Sleep Quality, measured as sleep without interruptions, improved in space. Based on a 10-point scale that gives higher scores for uninterrupted sleep, astronaut sleep patterns improved at the two time points in space (ISS01 and ISS02) compared to measurements on Earth (Before and After). These findings indicate that insomnia and sleep interruptions occur less frequently during time in space.


To get a more detailed look at the possible health benefits of better sleep quality during space flight, Otsuka and colleagues examined electrical waves indicative of heart rate variability. The team found that some of these electrical wave patterns rose more at night for astronauts in space than on Earth, pointing to better cardiovascular health during their space mission. Findings from monitoring heart rate variability show that spending time in space reverses aging-related decreases in heart rate variability, an indicator of improved heart health.

Higher Magnetic Fluctuations in Space Affect Nocturnal Heart Rate Dips

To find out what aspects of space travel might contribute to better sleep quality and improved cardiovascular well-being, Otsuka and colleagues chose to look at magnetic fields from Earth. As the International Space Station with the astronauts on board orbits Earth, magnetic fluctuations, altering magnetic intensities, from the planet arise. The research team found that as the intensity — the amplitude — of fluctuations increased, so too did the dip in heart rate at night, resulting in an increased circadian amplitude. These findings suggest that magnetic fluctuations from Earth may strengthen the body’s circadian rhythm and result in better quality sleep as shown by an enhanced circadian amplitude.

(Otsuka et al., 2021 | Scientific Reports) Higher magnetic fluctuations in space strengthen the body’s daily rhythm (circadian rhythm) by increasing the difference between daytime and nighttime heart rate (circadian amplitude). All three graphs show that the circadian amplitude increases with higher magnetic fluctuations (circadian amplitude). The left-most graph shows this relationship for a 12-hour (circasemidian) period, the middle graph for a 24-hour (circadian) period, and the right graph for a 48-hour (circaduodian) period. These findings show that as magnetic fluctuations from Earth increase, the circadian rhythm strengthens.

“We found that sleep quality was improved in space,” said Otsuka and colleagues.

They go on to say that magnetic stimulation in space may contribute to this better sleep quality, which is mirrored by previous research demonstrating that stimulating with magnetism at night induces deep sleep.

A limitation to the study that stands out is not confronting why some astronauts that have spent copious time in space have sleep and circadian rhythm problems. In order to investigate this issue in greater depth, space researchers need to follow astronauts for longer time periods after their space flights.

Can We Use Magnetism for an Anti-Aging Breakthrough?

Most people won’t have the opportunity to enter space during this generation, but what about future generations? If future space travel becomes more common, researchers will need more definitive answers about how long space travel-associated anti-aging effects last on Earth. They’ll also need to answer questions about how transitioning from space life to Earth affects the circadian rhythm and overall health. What’s more, the research on magnetism in space could lead to breakthrough anti-aging medical procedures that employ magnets without ever having to leave the ground!