Developing individualized ground testing protocols for use of sleep medications in spaceflight



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During spaceflight, sleep time are markedly reduced for astronauts. Sleep medications are used by astronauts during space mission for sleep. Spaceflight is an environment where abrupt alarm awakening is always a possibility and during that time high cognitive function and performance may be needed to prevent loss of life of crew. Zolpidem has been used on spaceflight after ground testing. The medication has been tested and studies have shown few side effects after a complete night of sleep. Few studies have been done on abrupt awakening after taking this medication. This study was done to test the effects of this medication on abrupt awakening after taking this medication and comparing to placebo. Seven subjects were selected and tested over two nights, one night with zolpidem and one night with placebo. Using a randomized single blind crossover design and testing cognitive function using a standard battery of computer based tests. Subjects were abruptly awakened after 2 hours of taking placebo and zolpidem. Subjects were videotaped, wore an actigraph and completed standard tasks and computer based testing bouts. When compared to placebo, on the night subjects were given zolpidem, subjects showed greater delay to alarm shut off, increased lapses of attention, and a large amount of variation between subjects. Actigraphy and video tape data correlated with the results of the computer based testing. Actigraph data also showed that subjects had similar average amounts of sleep with placebo and zolpidem. This study was not a traditional sleep study, it was operational study with practical testing of abrupt awakening and its effect on cognitive function. This study also provides evidence in support of developing a practical, individualized ground-based protocol for evaluating the cognitive performance deficits of sleep medications commonly used in spaceflight by NASA astronauts. The results of this study can be applicable to other fields where fatigue and sleep are an issue (military, shift work, etc). This protocol can also be used to test alertness medications in a similar way.