Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long (Sleep-Long) - 07.29.14

Overview | Description | Applications | Operations | Results | Publications | Imagery
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Science Objectives for Everyone
Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long (Sleep-Long) examines the effects of space flight and ambient light exposure on the sleep-wake cycles of crewmembers during long-duration stays on board the International Space Station.

Science Results for Everyone
Information Pending

This content was provided by Charles A. Czeisler, Ph.D., M.D., Laura K. Barger, Ph.D., and is maintained in a database by the ISS Program Science Office.

Experiment Details


Principal Investigator(s)

  • Charles A. Czeisler, Ph.D., M.D., Harvard Medical School, Boston, MA, United States
  • Laura K. Barger, Ph.D., Brigham and Women's Hospital, Boston, MA, United States

  • Co-Investigator(s)/Collaborator(s)
  • Joseph M. Ronda, Harvard Medical School, Boston, MA, United States
  • Kenneth P. Wright Jr., Ph.D., Boulder, CO, United States

  • Developer(s)
    Johnson Space Center, Human Research Program, Houston, TX, United States

    Sponsoring Space Agency
    National Aeronautics and Space Administration (NASA)

    Sponsoring Organization
    Human Exploration and Operations Mission Directorate (HEOMD)

    Research Benefits
    Information Pending

    ISS Expedition Duration
    September 2006 - March 2011

    Expeditions Assigned

    Previous ISS Missions
    Sleep-Short, a similar investigation was performed with short duration crewmembers during 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.

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    Experiment Description

    Research Overview

    • Previous research performed on Space Shuttle crewmembers shows that sleep-wake patterns are disrupted on orbit. The Sleep-Long experiment examines whether sleep-wake activity patterns are disrupted during long-duration stays on board the International Space Station (ISS).

    • A wrist-worn Actiwatch records the activity of the crewmembers and the ambient light they experience.

    • Data collected from sleep logs is used to evaluate the crewmember’s subjective evaluation of the amount and quality of their sleep and alertness.

    • This investigation will help define light requirements, sleep-shifting protocols and workload plans for future exploration missions. The results of the study will determine if further countermeasures to sleep disruption need to be tested.

    The success and effectiveness of manned spaceflight depends on the ability of crewmembers to maintain a high level of cognitive performance and vigilance while operating and monitoring sophisticated instrumentation. During short-duration space flights, crewmembers commonly experience sleep disruption and may experience misalignment of circadian (of or relating to biological processes occurring with a cycle of approximately 24 hours) phase during space flight. Both of these conditions are associated with insomnia, impairment of alertness, and cognitive performance.

    There is little information on the effect of long-duration spaceflight 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 on board the International Space Station (ISS). Subjects 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 are compared with baseline data collected on Earth before and after space flight. The data collected increases understanding of how space flight affects sleep as well as aids in the development of effective countermeasures for long-duration space flight.

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    Space Applications
    The information derived from this study will lead to a better understanding of the effects of space flight on sleep-wake cycles. The countermeasures that may be developed based on the findings of this study, could improve sleep during missions, which in turn will help maintain alertness and lessen fatigue of the crew during long-duration space flights.

    Earth Applications
    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.

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    Operational Requirements
    A total of 20 long-duration crewmembers are required as subjects for the experiment. Baseline data for each subject is collected for two weeks between Launch minus 120 (L-120) days and L–75, as well as from L-11 through L-0. Recovery in sleep patterns after space flight will be assessed from Return plus 0 (R+0) days to R+7.

    Operational Protocols
    Crewmembers put on the Actiwatches as soon as possible upon entry into orbit and wear them throughout the flight. Crewmembers maintain sleep logs; they are required to keep the log for seven consecutive days, every three weeks or during three separate weeks throughout the mission that meet specific schedule criteria. Crewmembers download data from the Actiwatches every 26 days and change the battery at the end of the increment. On the last day of the mission, crewmembers take off and stow the Actiwatches.

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    Results/More Information
    Analysis of the Sleep-Long data is ongoing.

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    Results Publications

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    Ground Based Results Publications

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    ISS Patents

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    Related Publications

      Monk TH, Buysse DJ, Billy BD.  Using daily 30-min phase advances to achieve a 6-hour advance: Circadian rhythm, sleep, and alertness. Aviation, Space, and Environmental Medicine. 2006 Jul; 77(7): 677-686. PMID: 16856351.

      Dijk D, Neri DF, Wyatt JK, Ronda JM, Riel E, Ritz-De Cecco A, Hughes RJ, Elliott AR, Prisk GK, West JB, Czeisler CA.  Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. 2001; 281(5): R1647-1664. PMID: 11641138.

      Mallis MM, DeRoshia CW.  Circadian Rhythms, Sleep, and Performance in Space. Aviation, Space, and Environmental Medicine. 2005; 76(6 Suppl): B94-107.

      Monk TH, Buysse DJ, Billy BD, DeGrazia JM.  Using nine 2-h delays to achieve a 6-h advance disrupts sleep, alertness, and circadian rhythm. Aviation, Space, and Environmental Medicine. 2004; 75: 1049-1057.

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    Related Websites
    Sleep Medicine at Harvard Medical School
    International Space Station Medical Project (ISSMP)

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    image This image of an Actiwatch Activity Monitor next to a ruler to demonstrate the size of the Actiwatch. Image courtesy of NASA.
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    image NASA Image: S104E5114 - Astronaut, Janet Kavandi on STS-104 wearing an Actiwatch on her right wrist for recording activities.
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    image NASA Image: ISS014E05119 - The Sleep-Long Actiwatch is visible on the left arm of Astronaut Michael Lopez-Alegria the Expedition 14 Commander. The Actiwatch monitors light and activity patterns of crewmembers.
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    image NASA Image: ISS014E12135 - Expedition 14 Flight Engineer, Astronaut Suni Williams, performs her daily tasks while wearing the Actiwatch device as seen on her left arm in the lower portion of this image.
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    image NASA Image: ISS015E09441 - Expeditions 14 and 15 Astronaut and Flight Engineer (FE-2), Sunita Williams, is seen here entering data at a computer workstation for the Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long (Sleep-Long) experiment in the U.S. Laboratory/Destiny.
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