Sleep-Wake Actigraphy and Light Exposure on ISS-12 (Sleep ISS-12) - 04.11.18

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
"Dim" or inappropriately timed lighting, or changes to sleep-wake timing (i.e., sleep shifting) may result in circadian misalignment. Previous research demonstrated that crew members experience circadian misalignment and widespread sleep deficiency during spaceflight on 6-month missions. The Sleep-Wake Actigraphy and Light Exposure on ISS-12 (Sleep ISS-12) experiment monitors ambient light exposure and crew member activity, and collects subjective evaluations of sleep and alertness, to examine the effects of spaceflight and ambient light exposure on sleep during a year-long mission on the International Space Station (ISS).
Science Results for Everyone
Information Pending

The following content was provided by Laura K. Barger, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Sleep

Principal Investigator(s)
Laura K. Barger, Ph.D., Harvard Medical School, Brigham and Women's Hospital, Boston, MA, United States

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

NASA 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
Earth Benefits, Scientific Discovery, Space Exploration

ISS Expedition Duration
March 2015 - March 2016

Expeditions Assigned

Previous Missions
Sleep-Short and Sleep-Long

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Experiment Description

Research Overview

  • Previous research performed on ISS crew members shows that sleep-wake patterns are disrupted on ISS missions that average about 6 months in duration.
  • Given that the duration of the ISS-12 mission is essentially twice as long as the typical ISS missions, it is unknown how sleep and the circadian system respond or adapt to that much time in space.
  • A wrist-worn Actiwatch Spectrum records the activity of the crew members and the ambient light they experience.
  • Data from the Actiwatch Spectrum can be used to estimate sleep duration. Bio-mathematical models of sleep and light can also be used to predict circadian phase.
  • Data collected from sleep logs is used to evaluate the crew member’s subjective assessment of the amount and quality of their sleep and alertness.
  • The Sleep-Wake Actigraphy and Light Exposure on ISS-12 (Sleep ISS-12) investigation is expected to help define light requirements, sleep-shifting protocols, and workload plans for future exploration missions. The results of the study may also help to determine if further countermeasures to sleep disruption need to be tested.

An inadequate quantity or quality of sleep may impair an astronaut's ability to maintain a high level of cognitive performance and vigilance while operating and monitoring sophisticated instrumentation during spaceflight. In order to understand sleep in space more completely, previous studies (Sleep-Short and Sleep-Long) were conducted with astronauts across multiple Space Shuttle (STS) and International Space Station (ISS) missions. Preliminary results indicate that the mean (+ SD) nightly sleep duration, as estimated from actigraphy, was 6.1 + 0.7 hours on ISS missions, which was significantly shorter than during Earth-based collections 90 days prior to the mission and one-week postflight (p<0.01). To obtain even this limited amount of sleep, 75% of ISS crew members reported taking sleep-promoting medications inflight. Circadian misalignment, as measured by Circadian Performance Simulation Software (CPSS), occurred during 20% of mission days and was significantly associated with increased use of sleep medication, decreased sleep quality and shorter sleep durations.

One US astronaut and one Russian cosmonaut plan to take part in a one-year ISS mission. Given that the duration of this mission is essentially twice as long as the nominal ISS missions, it is unknown how the mind and body, including sleep and the circadian system, might respond or adapt to that much time in space. Sleep and circadian alignment throughout the mission are to be estimated using Sleep Logs and a wrist-worn, monitoring device (Actiwatch Spectrum) to record activity and light exposure continuously throughout the mission. Findings from this long-duration mission are crucial to inform future exploration class missions.

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Space Applications
Crews on space missions frequently report fatigue, and studies show crew members experience circadian misalignment and sleep deficiency during spaceflight. Inadequate sleep could impair a crew member's ability to remain alert while operating complicated equipment. Results from the Sleep ISS-12 investigation are expected to improve understanding of how long-duration space flight affects sleep-wake cycles. Data from wrist-worn light and activity sensors determine how much crew members sleep in space, and how much light they are exposed to throughout the mission. Crew members also evaluate their own sleep quality and alertness. The results of the investigation are expected to help define light requirements, sleep-shifting protocols, and workload plans for future exploration missions, and may also help to determine whether additional sleep-disruption countermeasures are necessary to improve crew alertness and reduce fatigue.

Earth Applications
Millions of people, especially elderly people and shift workers, suffer from insomnia, experiencing difficulty initiating and/or maintaining sleep or waking up early. Results from this investigation may improve the technology for monitoring and diagnosing sleep disorders and assessing insomnia treatments.

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Operational Requirements and Protocols

This study only includes one or two subjects, depending on participation (there is a limited subject pool for the one-year mission). Crew members don Actiwatches ASAP upon arrival at ISS, and wear the watches continuously throughout the mission. Sleep Logs are completed using a Space Station Computer (SSC) within 15 minutes of awakening for seven consecutive days, every three weeks on-orbit. Actiwatch data is downloaded to the Human Research Facility Personal Computer (HRF PC) and downlinked no later than 35 days after previous initialization.

Crew members wear an Actiwatch Spectrum for the duration of the mission to monitor activity and light exposure.  Crew members download and configure Actiwatch Spectrums for data collection approximately every month.  Crew members complete Sleep Logs shortly after awakening for seven consecutive days every three weeks on-orbit.

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Decadal Survey Recommendations

Behavioral and Mental Health B2
Behavioral and Mental Health B3

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Results/More Information

Information Pending

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Related Websites

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