Dim light melatonin onset profile endotypes in a real-world clinical population with home-based, self-collected salivary assessments: Identification, distribution, and potential clinical relevance.

Academic studies suggest that self-assessment of circadian phase in home-based settings is viable. We implemented a pragmatic, home-based salivary dim light melatonin onset (DLMO) assessment protocol as a fee-based, clinical service model. The DLMO assessment protocol involved hourly self-collection of saliva samples scheduled relative to habitual bedtime, with a collection window beginning up to 7 h before bedtime and, when indicated, extending as late as 5 h post-bedtime. Patients received written and video instructions, and optional telehealth guidance. We performed two consecutive studies in which patient DLMO profiles from 2 datasets were evaluated. In study 1 (n = 253, 35.6% male, ages 18 to 83 years) compliance was evaluated via targeted telephone follow-up calls in cases where salivary profiles exhibited significant atypical features (e.g., absent or indeterminate melatonin onset, flattened curves, reported exogenous melatonin use) or when results appeared inconsistent with the clinical presentation as assessed by the referring provider. A reliable coding system was developed to classify circadian phase profiles. Results revealed 86 cases exhibited DLMO within the Predicted Onset Window (POW), 26 with Delayed Melatonin Onset, 28 with Advanced Melatonin Onset, 27 with Hypermelatoninemia, 36 with Hypomelatoninemia, and 43 with Irregular/Multipeak profiles. In study 2, the classification framework was applied to 300 additional cases (37.3% male, ages 18 to 89 years). Results revealed 110 cases exhibited DLMOs within the POW, 41 presented with Delayed Melatonin Onset, 46 with Advanced Melatonin Onset, 21 with Hypermelatoninemia, 33 with Hypomelatoninemia, and 42 with Irregular/Multipeak profiles. Of 159 patients with atypical profiles who self-reported symptoms prior to sampling, circadian phase profiles were concordant with at least one presenting complaint in 94.3% of cases. Implementation, methodological considerations, underlying biological context, and potential clinical implications are discussed.