1067 Personal Light Exposure is Associated with Circadian Phase and Sleep Timing in Young Adults with OCD and Delayed Bedtimes

Abstract Introduction Prior literature implicates delayed circadian rhythms in obsessive-compulsive disorder (OCD), and later indicators of circadian rhythms are associated with more severe OCD symptoms. However, factors that contribute to delayed circadian rhythms in OCD remain unexplored. As light is the primary entrainment cue for the central circadian clock, and unhealthy light exposure patterns delay circadian rhythms, we examined associations between personal light exposure and circadian phase and sleep timing in individuals with OCD and delayed bedtimes. Methods Young adults with OCD and a bedtime of 01:00 or later (N = 35; 30 female, mean age = 22.18 ± 4.12) monitored personal light exposure and sleep for 2 weeks via wrist actigraphy (Actiwatch Spectrum, Phillips Respironics) and completed a 10-hour in-laboratory salivary dim light melatonin onset (DLMO) assessment. The following light exposure variables were calculated using the LightLogR package: time above threshold (TAT) 250, 500, and 1000 photopic lux; mean timing of light exposure (MLiT) above 250, 500, and 1000 lux; first and last timing of light exposure (FLiT; LLiT) above 50 lux and their within-subject standard deviation (FLiT, LLiT 50 lux SD). DLMO was defined as the linear interpolated point in time at which melatonin levels rose 2 SD above the mean of 3 baseline values. Midsleep was measured by actigraphy. We used linear regression models covarying for solar photoperiod to examine associations between personal light exposure, DLMO, and midsleep. All p-values were FDR-corrected. Results Lower TAT 250, 500, and 1000 lux, later MLiT 250, 500, and 1000 lux, later FLiT 50 lux, and higher FLiT 50 lux SD were associated with later midsleep (p< 0.05). Later MLiT 250, 500, and 1000 lux and FLiT 50 lux were associated with later DLMO (p< 0.05). Conclusion Lower, later, and irregular light exposure were associated with later sleep timing, whereas only later timed light exposure was associated with later circadian phase. Personal light exposure patterns, particularly light timing, may contribute to delayed circadian rhythms in OCD. Circadian medicine treatments to address delays in OCD may benefit from prioritizing advancing light exposure timing. Support (if any) NIH T32HL149646; NIH K23MH137376; American Academy of Sleep Medicine Foundation 270-FP-22; International OCD Foundation