Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Short (Sleep-Short) - 10.21.14
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Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Short (Sleep-Short) examines how space flight affects astronauts’ sleep patterns during Space Shuttle missions. Advancing state-of-the-art technology for monitoring, diagnosing and assessing treatment of sleep patterns is vital to treating insomnia on Earth and in space.
Science Results for Everyone
Johnson Space Center, Human Research Program, Houston, TX, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
April 2005 - September 2011
Previous ISS Missions
Sleep-Short was previously operated on STS-104, STS-109, STS-111, STS-112, STS-113, STS-114, STS-121, STS-115, STS-116, STS-118, STS-120, STS-122, STS-123, STS-124, STS-125, STS-126, STS-127, STS-128, STS-129, STS-130, STS-131, and STS-132.
- Previous research conducted on Space Shuttle crewmembers shows that sleep-wake patterns are disrupted on orbit. A wrist-worn Actiwatch records the activity of the crewmembers, and the ambient light they experience.
- Daily sleep logs are used to evaluate the crewmembers’ subjective evaluation of the amount and quality of their sleep and alertness.
The success and effectiveness of manned space flight depends on the ability of crewmembers to maintain a high level of cognitive performance and vigilance while operating and monitoring sophisticated instrumentation. During short space flights, crewmembers commonly experience sleep disruption and misalignment of circadian (of or relating to biological processes occurring with cycles of approximately 24 hours) phase. Both of these conditions are associated with insomnia, and impairment of alertness and cognitive performance.
Relatively, little is known of the prevalence or cause of space flight induced insomnia in short duration missions. This experiment uses state of the art ambulatory technology to monitor sleep-wake activity patterns and light exposure in crewmembers on board the Space Shuttle. Subjects wear a small, lightweight activity and light-recording device (Actiwatch) for the entire duration of their mission. The sleep-wake activity and light exposure patterns obtained in-flight are compared with baseline data collected on Earth before and after space flight. The data collected leads to an understanding of the effects of space flight on sleep; as well as aids in the development of effective countermeasures for short duration space flight.
The information derived from this study will lead to a better understanding of the effects of spaceflight on sleep-wake cycles. The countermeasures that may be developed based on the findings of this study, could improve sleep cycles during missions which in turn will help maintain alertness and lessen fatigue of the Space Shuttle crewmembers.
A better understanding of insomnia is relevant to the millions of people on Earth who suffer nightly from insomnia. The advancement of state of the art technology for monitoring, diagnosing, and assessing treatment effectiveness is vital to the continued treatment of insomnia on Earth. This work has the potential to greatly benefit the health, productivity and safety of groups with a high prevalence of insomnia, such as shift workers and the elderly.
Short-duration (Space Shuttle) crewmembers volunteer for the experiment with the goal of obtaining as many volunteers as possible until the Space Shuttle program is retired. Baseline data for each subject is collected for two weeks between Launch minus 120 (L-120) days and L–75; also from L-11 through L-0. Recovery in sleep patterns after space flight is assessed from Return plus 0 (R+0) days through R+7.
Crewmembers put on Actiwatches as soon as possible upon entry into orbit (FD1) and wear the Actiwatches continuously throughout the flight. Sleep logs are completed each day within 15 minutes of awakening. On the last day of the mission, crewmembers remove and stow the Actiwatches.
Even when speeding at over seventeen thousand miles an hour, astronauts find it tough to catch enough Z’s. A comprehensive analysis of results, collected over a ten-year span, shows that Shuttle and International Space Station crew members have difficulty falling asleep and typically do not get the full amount of sleep recommended for them each night. Sleep researchers studied diary entries and rest/activity monitor data of 78 individual crew members from 80 shuttle flights (from 2001 to 2011) and 21 ISS missions (from 2005 to 2011) and found that, on average, space travelers get about 6 hours of sleep per night while in space and only slightly more during the data collect interval scheduled about three months prior to launch. The intensity of the pre-flight training and travel schedule may have contributed to insufficient sleep in the pre-flight data collection interval. During space missions, roughly three quarters of shuttle and ISS crew members reported taking sleep-promoting medication. Shuttle crew members reported taking sleep-promoting medications on about half of their nights in space, including nights prior to performing extra vehicular activity (EVA) work the next day which were extra mentally and physically demanding. The sleep-aid drug Zolpidem (brand name Ambien) was reported as the most often taken by shuttle crew members. The high prevalence of sleeping pill use during spaceflight, despite chronic sleep deficiency and improved sleeping conditions and quarters on the ISS, may suggest that some other aspect of the space environment, such as microgravity itself, might contribute to sleep disturbance. The use of sleep-promoting medication did not significantly increase the amount of sleep that astronauts obtained and only increased the sleep efficiency of shuttle crew members by about one percent. The minimal sleep improvement on nights when sleep-promoting medications were used emphasizes the need for further investigation into the stability, absorption, and effectiveness of such drugs in-flight. Sleep and the use of sleep-promoting medications during spaceflight needs further investigation, including the effect of chronic sleep deficiency and hangover effects from sleep promoting medications on operational performance, to develop and recommend best practices for ISS crew members. The sleep duration of crew members aboard long duration ISS missions was similar to that of crew members aboard short-duration shuttle missions. Monitoring and assessment of sleep duration and timing should continue in future spaceflight missions as a medical requirement, including collection of baseline data before astronaut selection for flight to estimate more accurately individual baseline sleep duration. Development of other more effective countermeasures to promote sleep in-flight is crucial, and might include scheduling modifications, strategically timed exposure to specific wavelengths of light and behavioral strategies to ensure adequate sleep, which is essential for maintaining optimal health, performance, and safety. Further research of sleep is planned for the future 1-year ISS missions, twice the normal length of previous ISS missions, which might provide information on trends in sleep over longer durations, which is especially relevant for future exploration class missions beyond low Earth orbit.
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Ground Based Results Publications
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Sleep Medicine at Harvard Medical School
International Space Station Medical Project (ISSMP)
This image shows an Actiwatch Activity Monitor next to a ruler to demonstrate the size of the Actiwatch. Image courtesy of NASA, Johnson Space Center.
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NASA Image: S104E5114 - Astronaut, Janet Kavandi on STS-104 wearing an Actiwatch on her right wrist for recording activities.
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