Assessment of dim light melatonin onset based on plasma and saliva samples.
Level 3 - non-randomized controlled study
Cross-sectional comparative diagnostic method validation in healthy volunteers
PubMed 35168448 · doi:10.1080/07420528.2021.2016796
What was done
Researchers developed and validated a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method following European Medicines Agency (EMA) guidelines to measure melatonin in plasma and saliva. They recruited 21 male and female volunteers aged 26–54 years and collected matched plasma and saliva samples at five time points between 20:00 and 00:00 hours. Dim light melatonin onset (DLMO) was defined as the time melatonin concentrations exceeded 20 pg/mL in plasma and 7 pg/mL in saliva, and values between both matrices were compared.
What was found
Plasma and salivary melatonin concentrations were significantly correlated (r = 0.764, p < .001), with a plasma-to-saliva concentration ratio of 2.87. The mean DLMO timing was 21:30 ± 0:45 hours in plasma and 21:34 ± 1:00 hours in saliva. The correlation between DLMO timing derived from plasma and saliva profiles was r = 0.679 (p < .05).
Why it matters
Salivary measurement using LC-MS/MS offers a non-invasive, reliable alternative to blood sampling for determining DLMO, facilitating circadian phase assessment in clinical and research settings.
Limits
The sample size was small (n = 21) and restricted to healthy volunteers, lacking validation in clinical populations with circadian rhythm sleep-wake disorders. Sampling was limited to a 4-hour window (20:00 to 00:00), which may fail to capture onset in individuals with advanced or delayed sleep phase.
Cited by
- supports Endogenous melatonin begins rising roughly two hours before habitual sleep time, peaks about one hour into sleep, and reaches its lowest level about two hours after waking.