A look at findings from 553 sleep clinic patients tested through our home-based salivary DLMO program, and why what patients feel isn’t always what their biology shows. 

Based on Stothard et al., Sleep Medicine (2026) · Rebis Health, BioFrontiers Center, Salimetrics Research & Technology Center, Beth Israel Deaconess Medical Center 

Dim Light Melatonin Onset (DLMO) is the gold-standard marker of a person’s internal circadian clock. Traditionally, measuring it meant hours in a clinic with repeated blood draws. Since 2022, Salimetrics has offered a physician-supervised, at-home salivary alternative: hourly saliva samples collected around a patient’s own bedtime, shipped to Salimetrics’ clinical lab for analysis. 

This paper reveals what those results actually show across 553 sleep clinic patients, spanning nearly three years of clinical application. 

Beyond “on time” or “late” 

The team moved past a simple early/late framework and defined six distinct melatonin profile types, with strong agreement between independent raters (92.3%): 

Amplitude-abnormal and irregular profiles were potentially tied to medication use: 87% to 96% of these patients were on melatonin-influencing medications or supplements, with a high frequently psychiatric medication use. 

The paradox: what patients feel isn’t always what their biology shows 

Only about one third of patients in this sleep-clinic population had a textbook circadian profile. And symptom reports were an unreliable guide to the underlying mechanism. 

Patients with an advanced melatonin onset were often the ones complaining of delayed sleep, the opposite of what their biology predicted. 

Irregular Sleep/Wake complaints turned out to be the most diagnostically specific symptom, directly matching the objective profile 69% of the time. Delayed Sleep, the most common complaint by far, turned out to be the poorest predictor of circadian phase, aligning only partially with objective results in 7 out of 10 cases.

Why it matters

If symptoms reliably predicted circadian phenotype, objective testing would add little. Instead, these findings support DLMO assessment as a way to identify biologically distinct patient subgroups who look alike on history and complaint alone, informing decisions on light therapy, melatonin supplementation, behavioral sleep, and medication timing. 

READ THE FULL STUDY 

Stothard, E.R., Schwartz, C.S., Okun, M.L., et al. (2026). Dim light melatonin onset profile endotypes in a real-world clinical population. Sleep Medicine. 

Read on ScienceDirect  → 

Published in Sleep Medicine, DOI: 10.1016/j.sleep.2026.109053