High dose melatonin increases sleep duration during nighttime and daytime sleep episodes in older adults.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 35436355 · doi:10.1111/jpi.12801
What was done
In a month-long randomized crossover trial using a forced desynchrony protocol, 24 healthy older adults (age >55, mean 64.2 ± 6.3 years) were assigned to receive 2 weeks of placebo and 2 weeks of either low-dose (0.3 mg) or high-dose (5.0 mg) melatonin 30 minutes before lights out. Polysomnography recorded sleep scheduled across both biological daytime and nighttime episodes.
What was found
The abstract reports qualitative outcomes without exact numerical effect sizes or confidence intervals: - Low-dose (0.3 mg) melatonin showed a trend toward increasing overall sleep efficiency, driven only by sleep during the biological day. - High-dose (5.0 mg) melatonin significantly increased sleep efficiency during both biological day and night. - The 5.0 mg improvement was mediated primarily by extending Stage 2 non-rapid eye movement sleep duration and slightly shortening awakenings.
Why it matters
Unlike younger adults who primarily respond to exogenous melatonin during the biological day, older adults experienced sleep efficiency gains during biological night with 5.0 mg melatonin, indicating potential utility as a sleep aid in older populations.
Limits
The sample size was small (n = 24) and restricted to healthy older adults in a laboratory forced-desynchrony protocol. The abstract reports no numerical values, variance, p-values, adverse event rates, or next-day cognitive performance measures.
Cited by
- supports Melatonin levels are naturally low during the daytime and high at night, causing circadian misalignment for individuals attempting to sleep during the day.