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Sleeping Short (NAG91036)
Principal Investigator
Research Area:
Behavior and performance
Species Studied
Scientific Name: Homo sapiens Species: Human

For various reasons, astronauts typically "sleep short" in space, seldom getting the 8 hours intended by the time line schedule. For some, this may not present a problem, because they are naturally short sleepers who can get by with 5 1/2 hours of sleep, for example, without any consequent daytime sleepiness. For others, sleeping short inevitably leads to impairments in mood, alertness, and ability to perform at full capacity. This project comprises a detailed investigation of "sleeping short" using ground-based studies of healthy men and women (20y-59y).

This study sought to address three critical questions:
1. Which countermeasure or combination of behavioral and physiological countermeasures will optimally mitigate specific performance problems associated with sleep loss and circadian disturbances during a Mars mission?
2. What individual biological and behavioral characteristics will best predict successful adaptation to long-term space flight of sleep and circadian physiology and the neurobehavioral performance functions they regulate?
3. What are the best methods for monitoring the status of sleep and circadian functioning and for assessing the effects of sleep loss and circadian dysrhythmia that are also portable and non-intrusive in the spaceflight environment? It has three aims which coincide broadly with the three years of proposed research.

In Year 01, we will develop a questionnaire/diary instrument (the "Sleep Length Index" - SLI) designed to identify those who are naturally short sleepers who can thrive on less than 6 hours of sleep (as opposed to those who restrict their sleep inadvisably and suffer from daytime sleepiness).

Year 02 will be concerned with determining the sleep and circadian rhythm, mood and performance differences between short sleepers (as identified by the SLI) and age and gender matched controls. The study will use an enhanced laboratory version of the 72-hour measurement block we have used in previous bedrest and astronaut studies.

Year 03 will test the efficacy of Modafinil as a countermeasure when medium sleepers are required to "sleep short." The drug will be tested in a double blind placebo controlled cross-over design, during a week of severe (40%) sleep restriction in the laboratory, involving detailed sleep, circadian, rhythm, mood, and performance measures. The project seeks not only to provide findings of operational benefit to NASA, but also to provide tools and information of general benefit for those of us on the ground who have to restrict the time available for sleep because of occupational and/or care giving commitments.

This experiment sought to provide questionnaire and diary instruments designed to assess habitual sleep need, and to assess the circadian regularity of human behaviors. It also had the aim of testing a particular pharmacological countermeasure (Modafinil) to reduced sleep amounts. In particular, the experiment involved a double-blind placebo-controlled trial of Modafinil as a countermeasure to five consecutive nights where sleep was restricted by 60% (i.e. to 40% of habitual durations).

The 3 specific aims are:

  1. development of questionnaire instruments to assess habitual sleep need and timing, to identify “naturally short sleepers”, assessing the personality and circadian characteristics, also the evaluation of the consequences of unmet sleep need (thus identifying short sleepers who were sleeping short unwisely);
  2. continued development and testing of an easily administered diary instrument to assess circadian regularity in human behavior (the 5-item Social Rhythm Metric SRM-5); and
  3. a double-blind placebo-controlled trial of Modafinil as a countermeasure to 5 consecutive nights where sleep was restricted by 60% (i.e. to 40% of habitual durations).

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Monk TH, Buysse DJ, Kennedy KS, Pods JM, DeGrazia JM, Miewald JM. Measuring Sleep Habits Without Using a Diary: The Sleep Questionnaire. Sleep. 2003 Mar 15;26(2):208-12[]

Monk TH, Buysse DJ, Rose LR, Hall JA, Kupfer DJ. The Sleep of Healthy People--A Diary Study. Chronobiol Int. 2000 Jan;17(1):49-60.[]

Monk TH, Buysse DJ, Welsh DK, Kennedy KS, Rose LR. A Sleep Diary and Questionnaire Study of Naturally Short Sleepers. J Sleep Res. 2001 Sep;10(3):173-9.[]

Monk TH, Frank E, Potts JM, Kupfer DJ. A Simple Way to Measure Daily Lifestyle Regularity. J Sleep Res. 2002 Sep;11(3):183-190.[]

Circadian rhythm

Data Information
Data Availability
Archive is complete. All data sets are on the Web site.
Data Sets + View data.

Attitude to Life scale
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
BRC 01/01/2003 12/31/2005 1095 days

Additional Information
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)
Proposal Source