Effect of 60 days of head down tilt bed rest on amplitude and phase of rhythms in physiology and sleep in men.

ABSTRACT: Twenty-four-hour rhythms in physiology and behaviour are shaped by circadian clocks, environmental rhythms, and feedback of behavioural rhythms onto physiology. In space, 24 h signals such as those associated with the light-dark cycle and changes in posture, are weaker, potentially reducing the robustness of rhythms. Head down tilt (HDT) bed rest is commonly used to simulate effects of microgravity but how HDT affects rhythms in physiology has not been extensively investigated. Here we report effects of -6° HDT during a 90-day protocol on 24 h rhythmicity in 20 men. During HDT, amplitude of light, motor activity, and wrist-temperature rhythms were reduced, evening melatonin was elevated, while cortisol was not affected during HDT, but was higher in the morning during recovery when compared

SUBMITTER: Bonmati-Carrion MA 

PROVIDER: S-EPMC10980770 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature