The optimal performance of astronauts during long-duration spaceflight depends heavily on their receiving adequate sleep. However, often due to operational issues, astronauts sleep only four-to-six hours per day. Dr. David F. Dinges will develop sleep-schedule countermeasures to ensure astronaut performance. Research will be garnered through a sleep study aimed at determining the benefit of naps occurring between periods of restricted sleep (similar to the schedule astronauts might experience in space). The study will look for ways to maximize sleep benefits by comparing the psychological and physical effects of various sleep and nap schedules.
Overview
Countermeasures to Neurobehavioral Deficits From Cumulative Sleep Deprivation During Spaceflight: Dose-Response Effects of Recovery Sleep Opportunities
Principal Investigator:
David F. Dinges, Ph.D.
Organization:
University of Pennsylvania School of Medicine
Technical Summary
The overarching goal of this project is to develop sleep schedule countermeasures to ensure optimal neurocognitive performance capability in astronauts during prolonged spaceflight. The primary aim is to determine the sleep dose-response effects of an acute change in sleep duration that occurs between two periods of chronic sleep restriction on neurocognitive performance functions, subjective states, and waking and sleep physiology.
The optimal performance of astronauts during extended-duration spaceflight depends heavily on achieving recovery through adequate sleep. There is now extensive evidence that astronaut sleep in space averages four to six and a half hours per day, and when critical operations (e.g., nighttime docking) are scheduled, very little sleep may be obtained during a day prior to the critical event. Ground-based experiments on healthy adults by our laboratory and others have demonstrated that limiting daily sleep duration to less than seven hours leads to cumulative deficits in neurocognitive performance and alertness. Within one to two weeks of sleep restriction at levels experienced by astronauts, performance deficits were serious; impairments on tasks requiring sustained attention, working memory and cognitive throughput reached levels equivalent to those found after one to two nights of total sleep loss.
The experiment will determine the countermeasure benefits for performance (during critical operations and subsequent days of sleep restriction) from an acute increase in sleep duration (i.e., single night of recovery sleep). In addition, generating sleep dose-response functions will provide critically needed information on the adverse performance consequences of an acute reduction in sleep duration below the chronic sleep-restriction level, which can occur in spaceflight prior to a day of critical operations. We will establish sleep dose-response curves for the immediate and delayed impact on neurobehavioral functions, of an acute (one night) change in sleep duration midway in a period of chronic sleep restriction. We will determine if performance recovery is complete after two nights of extended sleep, following chronic sleep restriction. In addition to the impact of a single night intervention, we seek to resolve whether complete neurobehavioral recovery from prolonged chronic sleep restriction is possible within two nights. We will investigate the relationship between sleep physiology and performance responses. We will investigate the effects of chronic sleep restriction, acute sleep intervention and recovery sleep on cardiovascular indices.
We are currently in the process of performing preliminary analyses on the data collected. Specifically, we are analyzing the neurobehavioral performance changes across the experimental protocol, and the recovery phase. We are also beginning analysis for the construction of the dose-response recovery curves from the chronic sleep restriction. We are in the process of manual scoring and analysis of the polysomnographic data.
At the current time, we are still analyzing the data and we have not yet fully constructed the dose-response recovery curves. Preliminary analysis, however, supports the hypothesis that as time in bed for sleep increases on the acute intervention night, following chronic sleep restriction, performance on the next day of simulated critical operations is improved in a sleep duration dose-response manner.
Data collection is complete and analysis of the data has commenced. We anticipate submitting several manuscripts to peer-review journals this year, which will begin to reveal the relationship between the varying durations of time in bed and recovery of waking neurobehavioral and physiological outcomes, following chronic partial sleep deprivation.
Earth Applications
The primary aim is to determine the sleep dose-response effects of an acute change in sleep duration that occurs between two periods of chronic sleep restriction on neurocognitive performance functions, subjective states, and waking and sleep physiology. The experiment will determine the countermeasure benefits for performance (during critical operations and subsequent days of sleep restriction) from an acute increase in sleep duration (i.e., single night of recovery sleep). The knowledge gained has the potential to change work scheduling and to further understanding of the effect of sleep loss and recovery on neurobehavioral function in many Earth-based safety-sensitive occupations, such as transportation workers (e.g., truck drivers, train conductors, airline pilots); operators in safety-sensitive industries (e.g., power plant control rooms); and military personnel.
This project's funding ended in 2008