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Scientists and payload developers can get more information on International Space Station research facilities by contacting the ISS Payloads Office or at 281-244-6187.

Actiwatch (Actiwatch)


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

Facility Overview

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Brief Facility Summary

The Actiwatch is a waterproof, nonintrusive, sleep-wake activity monitor worn on the wrist of a crewmember. The device contains a miniature uniaxial accelerometer that produces a signal as the subject moves. The data are stored in nonvolatile memory within the Actiwatch until they are downloaded for analysis.

Facility Manager(s)

Information Pending

Co-Facility Manager(s)

Information Pending

Facility Developer(s)

Cambridge Neurotechnology Ltd., Cambridge, MA, United Kingdom

Sponsoring Agency

National Aeronautics and Space Administration (NASA)

Expeditions Assigned


Previous ISS Missions

The Actiwatch has supported investigations on several space shuttle missions.

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Facility Description

Facility Overview

  • The Actiwatch monitor provides data on the amount of ambient light the subject is exposed to and the amount of movement produced by the subject.

  • The data collected from the Actiwatch is used to determine if space travel has an impact on the sleep-wake patterns of crewmembers.


The Actiwatch is a small, lightweight, wrist-worn device that simultaneously detects body movement and light intensity. It is used to evaluate sleep-wake adaptation and circadian cycle. The device is battery powered and can be used to collect data continuously in intervals ranging from 90 hours to 227 days depending on the sampling rate. The Actiwatch's internal, nonvolatile memory and programming allows it to store data indefinitely until it can be downloaded.

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Facility Operations

Crewmembers will put on the Actiwatch as required by the investigation, download data from the Actiwatch as needed, and change the battery at the end of the increment. The Actiwatch provides computer software for setup and data retrieval via a RS-232 serial port connection to a personal computer (PC). The PC must be IBM compatible and have a 486 processor (minimum); 8-MB RAM (minimum); Windows 95, Windows 98, or Windows NT 4.0 or higher; a 100-MB hard drive; a 9-pin RS-232 serial port; and Super Video Graphics Array 9 SVGA (800 x 600 pixels required to display all data displays).

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Results/More Information

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

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    Related Websites
  • Cambridge Neurotechnology Ltd.
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    image NASA Image: S109E6062: View of STS-109 Commander Scott Altman activating the Actiwatch while seated at the pilot's station on the orbiter Columbia's forward flight deck.
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    Information provided by the investigation team to the ISS Program Scientist's Office.
    If updates are needed to the summary please contact JSC-ISS-Program-Science-Group. For other general questions regarding space station research and technology, please feel free to call our help line at 281-244-6187 or e-mail at JSC-ISS-Payloads-Helpline.