The relationship between the dim light melatonin onset and sleep on a regular schedule in young healthy adults.
Level 4 - case-series / case-control
Observational cross-sectional correlational study in a single small cohort.
PubMed 15600132 · doi:10.1207/S15402010BSM0102_3
What was done
Sixteen young, healthy individuals maintained their habitual sleep schedules for one week. Researchers measured the relationship between dim light melatonin onset (DLMO) and habitual sleep parameters (bedtime, wake time, and sleep midpoint).
What was found
DLMO occurred approximately 2 hours before bedtime and 14 hours after wake time. DLMO was significantly associated with wake time (r = 0.77) and midpoint of sleep (r = 0.68), but bedtime was not significantly associated (r = 0.36).
Why it matters
Because direct DLMO assessment is costly and time-consuming, using wake time or sleep midpoint as an indirect marker could simplify the timing of circadian phase-shifting interventions like light therapy or exogenous melatonin in healthy populations.
Limits
The sample size was very small (n = 16) and restricted to young, healthy adults on regular schedules. The abstract does not report confidence intervals, exact p-values, or detailed DLMO testing protocols, and findings cannot be assumed to generalize to clinical or shifted populations.
Cited by
- supports Endogenous melatonin secretion typically begins 2 to 3 hours before habitual bedtime.