Sleep: Lost in Space?

Today's topic is sleep in outer space. But first, a little background. I recently returned from the World Future Society meeting in Boston. This is a fascinating convention with workshops and presentations ranging from how to achieve a sustainable environment, to the development of cyberspace into full emersion virtual reality, to speculation about the emergence of machine intelligence. Melchor Antunano presented one of the most interesting topics. He is with the FAA Civil Aerospace Medical Institute and the UN International Academy of Astronautics. He discussed medical issues with regard to commercial space flight, including space tourism.

It was striking to realize how many companies and how many countries are now pursuing commercial space business and space tourism. The first private piloted launch vehicle to reach outer space (the region above 100 km) was SpaceShipOne on June 21, 2004. The pilot was Mike Melvill who became the 433rd astronaut (generally anyone who has flown higher than 100 km) and the first private citizen to carry out a suborbital space flight. The vehicle itself was built by Burt Rutan's Scaled Compsites. This company is owned by Paul Allen, co-founder of Microsoft, through his company, Mojave Aerospace Ventures. The technology has been licensed by Sir Richard Branson of Virgin Atlantic Airways for use in the first commercial spaceline, Virgin Galactic. Thus began the new commercial venture of private manned space flight.

There are a number of other companies involved in the field of suborbital flight including Blue Origin, Canadian Arrow, PlanetSpace, Rocketplane, Starchaser Industries and Xcor. Other companies are already working on orbital space vehicles including BensonSpace, Shenzhou, SpaceX and Transformational Space. Bigelow Aerospace has launched two test orbital modules based on NASA's inflatable space habitat technology. One can only imagine the future view from the honeymoon suite of the Bigelow Orbital Hotel. The "Survey on Public Space Travel" by Futron/Zogby in 2006 estimated that the sub-orbital space tourism market could involve 13,000 flight participants and generate $650 million in revenue per year by 2021. The Obama administration has also recently given strong backing to private commercial space companies.

There is now a continuous human presence in space on board the International Space Station and hope that humans may push on to deep space with a flight to Mars within our lifetime. As more people, some of whom will be tourists rather than highly trained professional astronauts, enter space, a number of concerns arise with regard to medical issues during space travel. Up to now, most people flying in space have been young and in very good health. This may be less the case in the future as space tourism takes off.

Suborbital and orbital flights for non-specialists certainly present significant medical challenges. Long duration flights, say to Mars or on the space station, pose challenges for professional astronauts. What do you do if a crewmember has a heart attack? How do you cope with exposure to galactic cosmic radiation? What about having sex on long duration flights to Mars? What if a passenger has an undisclosed medical problem that becomes an issue on a flight? How will non-professionals cope with the very common problem of space motion sickness?

The list of issues considered was interesting- but sleep was not mentioned during the presentation. Sleep is, however, a very real concern to NASA. And while sleep issues may be relatively less important for sub-orbital space tourism, it will be more significant for those planning on orbital or lunar fly-by flights, both of which are currently being planned by existing space travel companies.

Space travel can affect sleep in many ways. Noise in the environment can make sleep difficult, there is a high level of arousal and novelty involved in space flight, and there are no normal day/night cycles that we can depend on to orient our bodies for regular sleep/wake schedules. Without the usual effects of gravity there is no necessarily up or down orientation. Space travelers must attach themselves to something such as a wall, seat or bunk bed to keep from floating away while asleep. Motion sickness, historically a common occurrence on space flights, is also a significant problem for getting to sleep.

Previous research indicates that sleep duration on missions may be short - about 6.5 hours per day with reduced subjective quality of sleep. Long duration flights of more than three months are especially challenging.

Astronauts on the space shuttle or space station typically sleep in sleeping bags. The space shuttle, soon to be retired from service, also has bunk beds. Sleep periods are usually scheduled for eight hours. Astronauts have reported dreams, nightmares, snoring and difficulty sleeping in space just as on earth. Astronauts on the shuttle are usually awakened by music sent by Mission Control. On the space station alarm clocks are used.

Problems with sleep can lead to fatigue and loss of performance in astronauts. This would also apply to civilian space tourists. According to NASA, astronauts frequently take sleeping medications but these can cause the same problems of "hang over" and decreased performance that people on earth experience. Melatonin has been investigated as a possible sleep aid for space travel.

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People may be thinking, "Why the heck would I be interested in the sleep of astronauts? It's here on Earth that sleep problems are hounding me!" As has often been the case in the past, research in the environment of outer space may not only benefit future astronauts, both government and civilian, but may also improve our understanding of sleep for people who never leave the planet. As an example, the extreme circadian effects of rapidly changing night and day while orbiting the earth (the sun rises and sets every 90 minutes for travelers in low earth orbit) may give information helpful for the treatment of earth bound jet lag or shift work. In space there is a unique opportunity for extensive physiological monitoring of astronauts that would be very difficult or even impossible for research participants on earth. For those who are interested in further information, the NASA web site has a great deal of useful material on all aspects of sleep in outer space.