The relationship between sleep and circadian-sleep phase angles based on dim light melatonin onset predicted from light and activity data.

Study objectives: The objective of this study was to evaluate the relationships between various sleep outcomes and circadian-sleep phase angles based on dim light melatonin onset predicted only from light and activity data.

Methods: Actigraphy and sleep questionnaire data were obtained from 2 independent datasets using the National Sleep Research Resource: the Multi-Ethnic Study of Atherosclerosis Sleep and the Hispanic Community Health Study/Study of Latinos Sueño Ancillary visit. Predicted dim light melatonin onset (pDLMO) was calculated using the extended Kronauer limit-cycle model. Separate phase angles were calculated as the length of time between pDLMO and sleep timing (sleep onset, sleep midpoint, and sleep offset). Relationships between each phase angle and the following sleep outcomes were assessed separately across datasets: total sleep time, total wake time in bed, sleep maintenance efficiency, self-reported sleep quality, and composite sleep health.

Results: Total sleep time and composite sleep health were associated with all 3 pDLMO-based phase angles (P < .001 for all). Phase angles for sleep onset and sleep offset were also associated with total wake time in bed (P < .001 for both). Each relationship was characterized by a clear peak associated with a specific phase angle. No relationships were identified between phase angles and sleep maintenance efficiency or self-reported sleep quality.

Conclusions: These findings suggest that pDLMO-based phase angles, which can be easily measured in naturalistic settings, can help identify circadian-sleep misalignment in clinical practice. Expanded use of pDLMO may therefore help guide personalized sleep and chronobiological interventions.

Citation: Reis DJ, Huang JB, Bahraini NH. The relationship between sleep and circadian-sleep phase angles based on dim light melatonin onset predicted from light and activity data. J Clin Sleep Med. 2025;21(8):1349-1361.