Sleep and the endogenous melatonin rhythm of high arctic residents during the summer and winter


  1. Paul, M.A.
  2. Love, R.J.
  3. Hawton, A.
  4. Arendt, J.
Corporate Authors
Defence Research and Development Canada, Toronto Research Centre , Toronto ON (CAN)
The seasonal extremes of photoperiod in high latitudes place particular strain on the human circadian system. Arctic residence has been associated with poor sleep in both summer and winter. The goal of the work reported herewas to study the circadian rhythms of individuals living in the high Arctic by measuring sleep variables and the timing of melatonin production. Two research trials were conducted in the built environment of CFS Alert (82º 29' 58" N). Participants wore motion logging devices (actigraphs), which measure ambient light as well as motion, for 1 week to provide data on sleep quantity, quality and light exposure. On the penultimate day of each trial, the participantswere maintained together in a gymnasiumwith lounge chairs and salivawas collected at regular intervals to measure melatonin and assess the dim light melatonin onset (DLMO), offset (MelOFF), 50% rise and fall times of thewhole profile and total production. In general, sleep duration was found to be significantly different between the January and June data collections at CFS Alert, with participants in June sleeping 50 min on average less each day compared to their January counterparts. In June sleep was mistimed in many subjects relative to circadian phase as evidenced by the melatonin rhythm. Exposure to bright evening light was the most likely causal factor and should be avoided in theArctic summer. The Arctic summer represents a particularly challenging environment for obtaining sufficient sleep.
endogenous melatonin;circadian desynchrony;fatigue;sleep hygiene;modeled cognitivie effectiveness
Report Number
DRDC-RDDC-2015-P008 — External Literature
Date of publication
13 Mar 2015
Number of Pages
Electronic Document(PDF)

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