Interdependence of Basic Components of the Sleep–Wakefulness Cycle and Cosmonauts’ Work–Rest Schedule

The paper considers the interdependence of wakefulness and sleep as two basic components of the functioning of a human’s diurnal body. Many experimental investigations stated the facts that troubled slumber affects quality of wakefulness, cognitive function specifically, while wakefulness impaired by emotional strain, work overload, and ensuing fatigue and overwork results in bad sleep. Russian flight rules rely on the interdependence of these diurnal components in setting a limit to a cosmonaut’s work time (6.5 h) and allotting sufficient time for sleep (8.5 h). In reality, these rules deviate because of scheduled night operations and systematic excessive workloads. Both of these factors provoke the risk of crew health impairment and performance degradation that should be kept in mind by planners of future orbital space exploration missions.