Severe atopic dermatitis, sleep disturbance, and low light exposure

Study objectives: Atopic dermatitis (AD) is a chronic inflammatory skin disorder in children. AD worsens at night, particularly in severe disease. Low light exposure contributes to inflammation, poor sleep and misalignment between circadian (24-hour) rhythms (biologic clocks) and social clocks (weekday-versus-weekend sleep timing), but has not been evaluated in AD. Our objective was to perform a cross-sectional study to determine whether there is an association between AD severity, recorded light exposure (RLE), and sleep measures in participants with AD and healthy controls.Methods: Secondary data analysis from two prospective observational studies of 74 participants ages 5-17 y.o. with severe AD compared to others (healthy controls and mild/moderate AD). Participants wore actigraphy watches for at least 1 weekday and one weekend. Rest/activity and RLE (lux) were obtained from the watches and were analyzed to estimate duration and quality of sleep/light exposure.Results: Participants (n=74) were on average 10.9 +/- 3.6 y.o., with 45% female, 17% no AD, 27% mild, 32% moderate, and 24% severe AD. On weekends, severe AD participants versus others fell asleep at a similar time (23:52 +/- 1:08 vs. 23:40 +/- 1:29 mean clock-time hours +/- SD; p=0.23), had similar sleep onset latency (8.2 +/- 8.7 vs. 12.7 +/- 16.9 minutes; p=0.28), but woke later (09:12 +/- 1:04 vs. 08:13 +/- 1:14 minutes; p<0.01) resulting in a later sleep-midpoint (04:32 +/- 0:53 vs. 03:49 +/- 1:08 minutes; p=0.02). Severe AD participants had lower levels of daytime RLE than others (mean-over-all-days: 1948.4 +/- 2130.0 vs. 10341.3 +/- 13453.8 lux; p=0.01) and throughout seasons, weekdays, or weekend, yet had similar nighttime RLE.Conclusion: Severe AD is characterized by low RLE and sleep disturbance. Low RLE could potentially induce circadian misalignment, contributing to inflammation and worse disease in severe AD. Low RLE can also reflect altered lifestyle and behavior due to atopic disease burden. Prospective studies are needed to test causality and the potential of bright light as an adjuvant therapy for severe AD.