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The role of circadian phase in sleep and performance during Antarctic winter expeditions
Author(s) -
Sletten Tracey L.,
Sullivan Jason P.,
Arendt Josephine,
Palinkas Lawrence A.,
Barger Laura K.,
Fletcher Lloyd,
Arnold Malcolm,
Wallace Jan,
Strauss Clive,
Baker Richard J. S.,
Kloza Kate,
Kennaway David J.,
Rajaratnam Shantha M. W.,
Ayton Jeff,
Lockley Steven W.
Publication year - 2022
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/jpi.12817
Subject(s) - circadian rhythm , free running sleep , melatonin , sleep (system call) , dark therapy , mood , delayed sleep phase , incidence (geometry) , sleep debt , physiology , medicine , endocrinology , psychology , insomnia , sleep deprivation , circadian clock , sleep disorder , light effects on circadian rhythm , psychiatry , physics , computer science , optics , operating system
The Antarctic environment presents an extreme variation in the natural light‐dark cycle which can cause variability in the alignment of the circadian pacemaker with the timing of sleep, causing sleep disruption, and impaired mood and performance. This study assessed the incidence of circadian misalignment and the consequences for sleep, cognition, and psychological health in 51 over‐wintering Antarctic expeditioners (45.6 ± 11.9 years) who completed daily sleep diaries, and monthly performance tests and psychological health questionnaires for 6 months. Circadian phase was assessed via monthly 48‐h urine collections to assess the 6‐sulphatoxymelatonin (aMT6s) rhythm. Although the average individual sleep duration was 7.2 ± 0.8 h, there was substantial sleep deficiency with 41.4% of sleep episodes <7 h and 19.1% <6 h. Circadian phase was highly variable and 34/50 expeditioners had sleep episodes that occurred at an abnormal circadian phase (acrophase outside of the sleep episode), accounting for 18.8% (295/1565) of sleep episodes. Expeditioners slept significantly less when misaligned (6.1 ± 1.3 h), compared with when aligned (7.3 ± 1.0 h; p < .0001). Performance and mood were worse when awake closer to the aMT6s peak and with increased time awake (all p < .0005). This research highlights the high incidence of circadian misalignment in Antarctic over‐wintering expeditioners. Similar incidence has been observed in long‐duration space flight, reinforcing the fidelity of Antarctica as a space analog. Circadian misalignment has considerable safety implications, and potentially longer term health risks for other circadian‐controlled physiological systems. This increased risk highlights the need for preventative interventions, such as proactively planned lighting solutions, to ensure circadian alignment during long‐duration Antarctic and space missions.