Sleep deficits in the High Arctic summer in relation to light exposure and behaviour – Use of melatonin as a countermeasure

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Authors
  1. Paul, A.M.
  2. Love, R.J.
  3. Hawton, A.
  4. Brett, K.
  5. McCreary, D.R.
  6. Arendt, J.
Corporate Authors
Defence Research and Development Canada, Toronto Research Centre , Toronto ON (CAN);Surrey Univ, Guildford (England);Canadian Forces Health Services, Halifax NS (CAN)
Abstract
There are conflicting reports regarding seasonal sleep difficulties in polar regions. Herein we report differences in actigraphic sleep measures between two summer trials (collected at Canadian Forces Station Alert, 82.5°N, in 2012 and 2014) and evaluate exogenous melatonin for preventing/ treating circadian phase delay due to nocturnal light exposure. Methods: Subjects wore actigraphs continuously to obtain sleep data. Following seven days of actigraphic recording the subjects filled out questionnaires regarding sleep difficulty and psychosocial parameters and subsequently remained in dim light conditions for 24 hours, during which saliva was collected bihourly to measure melatonin. During Trial 2, individuals who reported difficulty sleeping were prescribed melatonin, and a second saliva collection was conducted to evaluate the effect of melatonin on the circadian system. Results: Trial 1 subjects collectively had late dim light melatonin onsets and difficulty sleeping; however, the Trial 2 subjects had normally timed melatonin rhythms, and obtained a good quantity of highquality sleep. Nocturnal light exposure was significantly different between the trials, with Trial 1 subjects exposed to significantly more light between 2200 and 0200h. Melatonin treatment during Trial 2 led to an improvement in the subjective sleep difficulty between the pre- and post-treatment surveys; however there were no significant differences in the objective measures of sleep. Conclusions: The di
Keywords
endogenous melatonin;circadian desynchrony;fatigue;sleep hygiene;modeled cognitivie effectiveness
Report Number
DRDC-RDDC-2015-P061 — External Literature
Date of publication
01 Aug 2015
Number of Pages
8
DSTKIM No
CA040895
CANDIS No
801975
Format(s):
Electronic Document(PDF)

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