Effects of outdoor natural light exposure on sleep quality in the elderly

Abstract

Introduction: One of the serious outcomes associated with ageing is the high prevalence of age-related sleep disturbances detrimentally influencing general well-being in the elderly. Whilst underexposure to diurnal bright light appears to be a reason for disturbed sleep in old age, further empirical evidence is required to confirm such a relationship. Materials and Method: In order to contribute to our current understanding of the subject, a study was conducted in a long-term care facility in Istanbul, Turkey. Participating elderly residents (N = 39) were exposed to natural light outdoors (> 10,000 lx) for 40 minutes in the morning on 17–21 June and 1–5 July 2019, and they were asked to report on their sleep quality by completing various questionnaires throughout the study. Results: The results of the study demonstrated a significant difference (p < 0.05) between the pre- and post-treatment scores of the participants. Moreover, the participants reported significantly less (p < 0.05) disturbed sleep in the second period during which they were exposed to approximately 63% more natural light. Conclusion: Based on our findings and those of other research groups, it is possible to conclude that light, or more specifically natural light, should be considered as an independent factor affecting sleep and, thus, general well-being in old age. © 2020 Elsevier B.V., All rights reserved.