A question to consider as you read . . .Thinking about weightlessness and mental/emotional stress, do you think you'd have trouble sleeping in space?
Vocabulary that will help you understand this section
In space, astronauts commonly experience difficulty in sleeping. Resulting alterations in sleeping patterns can lead to deterioration of alertness and cognitive performance during the active hours of the work day. The Sleep Team, composed of two highly complementary and tightly integrated experiments by Dr. Charles Czeisler and Dr. John West, intends to evaluate the altered sleep patterns of crewmembers during space flight. The results of this study are expected to lead to a better understanding of sleep mechanisms during space flight and possibly to the development of a new treatment for sleep disturbances associated with space flight. Additionally, the information learned from this work can be applied to other groups of individuals with a high prevalence of insomnia, such as shift workers and the elderly.
Dr. Czeisler's study will evaluate the effect that melatonin has on the crewmember's ability to sleep, whereas Dr. West's study will determine the cause of sleep disruptions related to breathing. The combined studies are expected to result in data that can be directed toward minimizing sleep disturbances and improving the quality of sleep during space flight for future crewmembers.
Dr. Czeisler's Study
Dr. Czeisler is studying the impact of melatonin, a naturally occurring hormone, on sleep and daytime performance. In flight, crewmembers will be given melatonin or a placebo in the form of a pill. Crewmembers will then be studied to determine if the administration of melatonin, as compared to the placebo, results in improved sleep. Using a questionnaire, subjective data will be collected about sleep quality, mood and alertness. Quantitative information on quality of sleep will be generated as the subjects sleep, by measuring the electric impulses of the brain, muscles, eyes, and heart. Supporting data will include an analysis of urine collected, allowing for determination of urinary melatonin excretion levels and body temperature measurements to document circadian rhythm phases.
Dr. West's Study
Dr. West will focus on correlating changes in respiratory patterns and the oxygen level of blood during sleep with sleep interruptions caused by internal mechanisms. During space flight, the patterns of the chest and abdominal wall motion are altered. Dr. West believes the alteration is due to an increased effort to breathe in order to maintain oxygen levels, and that this increased effort in return causes the astronaut to awaken. In flight, crewmembers breathe varying gas mixtures while gas compositions and flow rates are recorded. Also, motions of the rib cage and abdomen, arterial oxygen saturation, arterial blood pressure, and electrocardiogram data are recorded.