Skip to page content Mission Information


Sleep-Wake Actigraphy and Light Exposure During Spaceflight (9802394)
Principal Investigator
Research Area:
Species Studied
Scientific Name: Homo sapiens Species: Human

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. Astronauts, however, commonly experience sleep disruption and may experience misalignment of circadian phase during space flight. 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, and less is known about the effect of long-duration space flight on sleep and circadian rhythm organization. This experiment uses state-of-the-art ambulatory technology to monitor sleep-wake activity patterns and light exposure in crewmembers aboard the International Space Station (ISS). Crewmembers wear a small light-weight activity and light recording device (Actiwatch) for the entire duration of their mission. The sleep-wake activity and light exposure patterns obtained in flight will be compared with baseline data collection collected for two weeks between 120 days before launch (L-120) and L-75 and from L-11 through L-0. Recovery from space flight was assessed from the day of landing (R+0) through R+7. These data should help researchers better understand the effects of space flight on sleep, as well as aid in the development of effective countermeasures for both short- and long-duration space flight.

The primary objective of this experiment was to document the effects of long-duration space flight on sleep-wake activity patterns using a wrist-worn Actiwatch. Additional objectives were to measure the ambulatory light exposure of individual crewmembers and to evaluate the effects of space flight on crewmembers' subjective evaluation of the amount and quality of their sleep.

The information derived from this study will help to better understand the effects of space flight on sleep, as well as aid in the development of effective countermeasures for long-duration space flight. Moreover, a better understanding of the etiology of insomnia is relevant to the millions of people on Earth who suffer nightly from insomnia. Finally, 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 and in space.

++ -- View more

Barger LK, Flynn-Evans EE, Kubey A, Walsh L, Ronda JM, Wang W, Wright KP Jr, and Czeisler CA. Prevalence of sleep deficiency and use of hypnotic drugs in astronauts before, during, and after spaceflight: An observational study. Lancet Neurology. 2014. September; (13) 9, 904-912. []

Flynn-Evans EE, Barger LK, Kubey AA, Sullivan JP, and Czeisler CA. Circadian misalignment affects sleep and medication use before and during spaceflight. npj Microgravity 2, Article number: 15019 (2016). [DOI]

Circadian rhythm

Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
Data Sets+ Request data

Caffeine consumption
Medications (taken)
++ -- View more

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 14 09/18/2006 04/21/2007 215 days
Expedition 15 04/07/2007 10/21/2007 197 days
Expedition 16 10/10/2007 04/19/2008 192 days
Expedition 17 04/08/2008 10/23/2008 198 days
Expedition 18 10/12/2008 04/17/2009 187 days
Expedition 19 03/26/2009 10/11/2009 199 days
Expedition 20 05/27/2009 10/11/2009 137 days
Expedition 21 10/11/2009 12/01/2009 51 days
Expedition 22 11/30/2009 03/18/2010 109 days
Expedition 23 03/18/2010 06/01/2010 75 days
Expedition 24 06/01/2010 09/25/2010 117 days
Expedition 25 09/24/2010 11/25/2010 31 days
Expedition 26 11/26/2010 03/16/2011 111 days

Human Research Program (HRP) Human Research Roadmap (HRR) Information
Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at:

+ Click here for information of how this experiment is contributing to the HRP's path for risk reduction.

Additional Information
Other Key People
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Pamela A. Bieri
Institutional Support
National Aeronautics and Space Administration (NASA)
Alternate Experiment Name
Sleep Long
DSO 634L
178012 1_2
Proposal Date
Proposal Source
Hardware Items