Circadian regulation of physiology: Relevance for space medicine

The circadian clock is an endogenous time-generating system accountable for the synchrony between the internal and the geophysical time. In recent years, chronobiology research has demonstrated that the circadian regulation of numerous molecular and cellular processes leads to a temporal control of physiology and behaviour. These findings alert to the negative impact on health caused by a disrupted internal timing.

In this review we address the relation between atypical external factors in long-term space flights (or other extreme environments) and circadian clock misalignment, stressing the need of establishing preventive measures to minimize the effect on human health and performance. For this purpose, daily activities of astronauts (or humans living in extreme environments) could be planned according to the individual’s internal biological time, which can be achieved through the synergy between the molecular characterization of the circadian clock and computational predictive mathematical models.