Day-time melatonin administration: effects on core temperature and sleep onset latency.
Level 2 - randomized trial
Controlled clinical trial comparing daytime melatonin to placebo in healthy humans.
PubMed 8956204 · doi:10.1046/j.1365-2869.1996.t01-1-00006.x
What was done
Sixteen healthy young males received either a 5 mg oral formulation of melatonin or placebo at 14:00 hours. Core body temperature was continuously recorded, and sleep onset latency to stage 1 (SOL1) and stage 2 (SOL2) was measured using an hourly multiple sleep latency test (MSLT).
What was found
Compared to placebo, melatonin significantly decreased core body temperature starting 1.5 hours after administration for a duration of 6 hours. Between 15:00 and 18:00 hours, this temperature reduction was associated with a 40% reduction in mean SOL1 and a 25% reduction in mean SOL2.
Why it matters
This study provides experimental evidence linking melatonin-induced hypothermia to reduced sleep onset latency, supporting the concept that thermoregulatory shifts mediate daytime sleep propensity.
Limits
The sample size is small (n = 16) and limited to young healthy males. The abstract does not provide exact baseline temperature numbers, absolute latency durations, measures of statistical dispersion, or details regarding randomization and blinding procedures.
Cited by
- supports Falling asleep and maintaining deep sleep requires core body temperature to decrease by approximately 1 to 3 degrees, while waking energized requires a 1 to 3 degree temperature increase.