An exploratory study examining the associations between sunlight exposure, sleep behaviours and sleep outcomes during an Arctic summer

Abstract

Few evidence-based recommendations exist for maintaining healthy sleep during Arctic summers. Our study aimed to examine associations between sleep hygiene, sunlight exposure and sleep outcomes in workers living in and/or near the Arctic Circle during a 24-h light period. A survey was administered July 2017 to 19 workers at 3 Arctic base camps in Northeastern Alaska. Participants with poorer sleep hygiene reported increased sleepiness (r=.62, p=0.01); this correlation remained moderately strong, albeit not statistically significant (NS), after controlling for shift work (r=.46, p=0.06). No other statistically significant correlations between sleep hygiene and sleep outcomes were found. Weekly daytime (<8pm) and evening (>8pm) sunlight exposures, estimated from daily self-reported sunlight exposures for a typical workday and day off, were dichotomised, based on means, into: longer (>45 h/week) versus shorter (<45 h/week) daytime exposures, and longer (>16 h/week) versus shorter (<16 h/week) evening exposures. Participants reporting longer, versus shorter, weekly daytime sunlight exposure had statistically significantly (Mann-Whitney U=18.00, Z= −1.98, p≤0.05) decreased median sleep duration (6 h, 18 min versus 8 h, respectively) during the past month. Correlations of r≥.3 for longer, vis-à-vis shorter, daylight sunlight exposure suggest it could be related to poorer sleep outcomes, such as insufficient sleep and sleep quality, yet, as these correlations were NS, future work is needed to determine this. Weak or no correlations (and NS differences) were found for longer, versus shorter, weekly evening sunlight exposure and sleep outcomes. Findings support previous research suggesting self-regulation behaviours alone are not protective against poor sleep in Arctic environments. Sleep outcomes did not differ statistically significantly by evening sunlight exposure length. Longer weekly daytime sunlight exposure, versus shorter, was significantly associated with decreased sleep duration. Results from this exploratory study should be confirmed in studies using larger sample sizes.