The submariners’ sleep study: a field investigation of sleep and circadian hormones during a 67-day submarine mission with a strict 6-h-on/6-h-off watch routine

Feb 10, 2022Journal of applied physiology (Bethesda, Md. : 1985)

Sleep and daily hormone patterns during a 67-day submarine mission with a strict 6-hour work/rest schedule

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

A 67-day undersea mission showed distinct differences in sleep patterns and hormone secretion among participants.

Participants exhibited a biphasic sleep pattern with unequal distributions of total sleep time and sleep efficiency between two sleep blocks.
Melatonin secretion did not adjust to the watch standing blocks and followed an endogenous circadian rhythm, suggesting a phase shift.
Cortisol secretion aligned with the biphasic work-sleep shift routine, indicating some level of adjustment.
Findings suggest a disconnect between human physiological responses and operational requirements, particularly regarding melatonin and cortisol adjustments.
The study underscores the need for a watch standing schedule that better accommodates human physiology.

AI simplified

The submarine working and living environment is an isolated, confined, and extreme (ICE) environment where a continuous on-watch is required to fulfill the tactical objectives. The current study examined whether a physiological and behavioral adjustment to an operational watch standing scheme occurred in terms of hormonal secretion (i.e., melatonin and cortisol) and sleep during a 67-day undersea mission. The crew followed a strict scheme of watch-on blocks at 0:00-06:00 h and at 12:00-18:00 h (, diurnal sleep group) or watch-on blocks at 06:00-12:00 h and 18:00-24:00 h (, nocturnal sleep group). We sampled saliva during the operational blocks over a 24-h period atof the mission and collected sleep actigraphy data during the entire mission in 10 participants. Sleep showed a biphasic split pattern with significantly unequal distributions of total sleep time (TST) and sleep efficiency (SE) between the two sleeping blocks, i.e., one long and one short sleep bout. Melatonin secretion showed no adjustment at the end of the mission to the watch standing blocks, following an endogenous circadian rhythm independent from the social zeitgebers with indications of a phase shift. Cortisol secretion however matched the biphasic work-sleep shift routine. Human physiology does not fully obey operational needs and there are differences in adjustment between melatonin and cortisol. A watch standing schedule that provides a balance between physiology and operationality still needs to be established. The potential adaptation effects of bright light therapy and melatonin supplementation should be investigated in future research.The current study has a unique character due to the field context in which the data were collected. Data on long-term submarine missions are scarce and valuable in terms of operational and ecological validity. Moreover, the results are important both from a scientific and operational point of view, showing that human physiology does not fully obey operational needs and that there are differences in adjustment dependent from the type of circadian hormone. group 1group 2day 55NEW & NOTEWORTHY

Full Text

Full text is available at the source.

View full text ↗

The submariners’ sleep study: a field investigation of sleep and circadian hormones during a 67-day submarine mission with a strict 6-h-on/6-h-off watch routine

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief