Sleeping Better in Space: Sleep Studies and
Clinical Trials of Melatonin as a Hypnotic
Astronauts can have difficulty sleeping during space flight. Most likely,
a combination of factors contributes to these sleep problems. These factors
include the novelty and excitement of space flight itself, ambient noise
in the close confines of the spacecraft, and the absence of normal day/night
cycles. In fact, the sun rises and sets every 90 minutes in low Earth
orbit.
Sleep disruption can lead to fatigue and decrements in performance for
astronauts. To improve sleep quality, many
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This astronaut prepares
for sleep after donning the electrode net and physiologic moniters
that will assess the quality of his sleep.
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astronauts take sleep aids such as the benzodiazepine hypnotic Restoril.
These medications, however, may have undesirable side effects on performance
and mental alertness. In the search for a better sleep aid, researchers
have targeted melatonin, a naturally occurring hormone produced in the
pineal gland of the brain. Ground-based research indicates that melatonin
may facilitate sleep, an attribute that is particularly important if astronauts
are scheduled to sleep at a time of day when their bodies are not producing
the hormone.
The investigation, Clinical Trial of Melatonin as a Hypnotic, will determine
whether the use of melatonin improves the quality of sleep for astronauts
during space flight, thereby improving their ability to perform the mentally
challenging and physically rigorous tasks required of them. Although melatonin
is currently available in health food stores as a food supplement, the
dosages available are typically 10-20 times greater than levels found
in the human body. This study is designed to evaluate whether a near-physiologic
dose of the hormone can be effective in promoting sleep.
Aside from improving the sleep quality of astronauts during space flight,
this research has direct application for many people here on Earth. Sleep
disorders affect a wide range of people from those who perform challenging
jobs involving night shift work to the many Americans who often experience
sleep disorders as they age. This investigation will be the first to assess
the effects of space flight on the sleep patterns of an older astronaut.
The sleep quality and mental functions of crewmembers will be assessed
before, during, and after flight. Before each sleep period of the mission,
crewmembers will take an unmarked
capsule that contains either melatonin or placebo. The crewmembers will
wear an unobtrusive wrist actigraph to monitor their sleep-wake cycle.
In addition, astronauts’ sleep will be characterized more completely via
recordings that assess several sleep parameters. During each of the four
intensive monitoring sessions, crewmembers will wear an electrode net
on their heads . These electrodes will be connected to a Digital Sleep
Recorder that monitors brain waves, eye movements, muscle tension, body
movements, and respiration. Astronauts will be assisted in troubleshooting
this high-tech setup by an artificial intelligence computer system developed
jointly by the Massachusetts Institute of Technology and NASA Ames.
Other factors related to sleep quality, such as mental performance and
environmental parameters, will also be assessed to complement data collected
with the sleep recorder. After each night of wearing the electrode net,
crewmembers will use a laptop computer to fill out a record of sleep quality
and complete a 20-minute battery of cognitive performance and subjective
mood tasks. Body temperature will be recorded continuously from flight
day 2 through flight day 9 using an ingested radio-telemetry pill. These
readings will be compared with similar recordings pre- and postflight.
Ambient light levels in work and rest areas will also be measured to correlate
environmental light cues with sleep patterns. Crew members will don the
electrode net for six nights of monitoring before flight and three nights
of monitoring after flight to complement the data collected inflight.
Points of Contact:
Principal Investigator
Charles A. Czeisler, Ph.D., M.D.
Harvard Medical School and Brigham and
Women’s Hospital
Boston, MA
Co-Investigators
Rod J. Hughes, Ph.D.
Joseph M. Ronda, M.S.
Harvard Medical School and Brigham and
Women’s Hospital
Boston, MA David
F. Neri, Ph.D.
NASA Ames Research Center
Mountain View, CA
John B. West, M.D., Ph.D.
G. Kim Prisk, Ph.D.
Ann R. Elliott, Ph.D.
University of California, San Diego
San Diego, CA
Laurence R. Young, Sc.D.
Massachusetts Institute of Technology
Cambridge, MA
FS-1998-09-010JSC (PDF
Format)
Curator: Kim Dismukes
Responsible NASA Official: John Ira Petty
Updated: 24 October 1998
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