Feasibility of a contactless, self-directed, home-based dim-light melatonin onset protocol: the Circadia pilot study

To test the feasibility of a self-directed, in-home, contactless salivary dim light melatonin onset (DLMO) assessment protocol to remotely measure endogenous circadian phase in participants with circadian rhythm disorders and healthy controls.

The 4-6-week protocol involved sleep, activity, and light tracking, sleep diaries, questionnaires, and two self-directed at-home salivary sample collections for DLMO one week apart with objective compliance measures. Individuals participated remotely using an online portal and received a mailed kit. The study population included five cases with Circadian-Rhythm Sleep-Wake Disorders and five controls ages 27-63.

Salivary DLMO times could be calculated for 14/20 assessments, resulting in 8/10 participants with at least 1 valid DLMO and 6/10 having valid DLMOs for both. Failures in DLMOs resulted from compliance errors (eg, bright light levels) or consistently below/above threshold melatonin levels. After completing the DLMO collections, 70% of participants felt confident after completing DLMO 1, while 90% felt confident after DLMO 2. DLMO occurred on average at 24.08 hours (SEM = 1.10 hours) for four participants with Delayed Sleep Wake Phase Disorder, and at 21.37 hours (SEM = 0.71 hours) for five controls. The first and second DLMOs were strongly correlated (r = 0.98, p < .001).

Our results indicate that contactless, self-directed, at-home DLMO assessments are feasible, reliable, and capable of detecting clinically relevant differences in circadian timing. The current protocol may serve as a framework to reliably and scalably assess circadian phase in both clinical and general populations.