In a small study of healthy adults 55 years and older, melatonin 5 mg increased total sleep time compared to placebo.
Although recent research from the University of Cambridge and Fudan University has found that seven hours is the ideal amount of sleep, many Americans get less. In fact, 2014 CDC data found that 35.2% of US adults get less than 7 hours of sleep. Of course, many of us could use some help to fall asleep faster and sleep better.
Melatonin is one of the most widely used dietary supplements in the United States. Among older adults, its use has tripled over the past two decades. However, there is no consensus on the correct dosage of melatonin, and studies of its effects on sleep quality in older adults have yielded mixed results. Researchers at Brigham and Women’s Hospital conducted a study in 24 healthy, older adults to evaluate whether high-dose or low-dose melatonin supplementation could improve sleep. The team found that the higher dose had a significant impact, increasing total sleep time by more than 15 minutes for nighttime sleep and by half an hour for daytime sleep compared to placebo. The results will be published in The Journal of Pineal Research.
melatonin is a hormone that the pineal gland in your brain produces in response to darkness. It helps in timing your circadian rhythm (24-hour internal clock) and controlling the sleep-wake cycle. Exposure to light at night can block melatonin production.
“Sleep deprivation becomes more common with age, and given the downsides of many prescription sleep aids, many older adults report taking melatonin,” said senior author Charles Czeisler, PhD, MD, head of Brigham’s Division of Sleep and Circadian Disorders. “But we have little evidence on the effects of melatonin on sleep health in older adults. Our study provides new evidence and insight, and highlights the importance of considering dosage and timing when considering the effects of supplements such as melatonin, particularly in the elderly.”
The body naturally produces the hormone melatonin, which helps regulate a person’s sleep-wake cycle with day and night. Melatonin levels are highest at night. But in older people, hormone levels are often lower. Exogenous melatonin is sold over the counter and can be taken at bedtime as a dietary supplement, usually in a pill or capsule form.
To rigorously assess the effects of melatonin supplements, the study authors focused on healthy, older adults with no history of major sleep disorders. All potential participants were screened for sleep disorders. The study involved 24 participants (13 women, 11 men) aged between 55 and 78 years.
During the one-month study period, participants lived in individual study rooms with no windows, clocks, or other indication of the time of day. Participants followed a forced desynchrony protocol — instead of experiencing 24-hour cycles of day and night, they were on schedules of 20-hour cycles to unravel the effects of resting activity from the circadian clock. This allowed sleep to be scheduled both at night and during the day, but with a similar duration of waking before each sleep. Participants were randomly assigned to receive a placebo pill for two weeks and either a low (0.3 mg) or high (5 mg) dose of melatonin for two weeks 30 minutes before bedtime. Researchers used polysomnography to record brain waves, eye movements, muscle tone and other key sleep metrics.
The team found that the low dose of melatonin did not result in a statistically significant change in total sleep time and that the observed changes were due to when sleep was scheduled during the biological day. The participants who took the 5 mg dose had a significant increase in total sleep time and sleep efficiency, regardless of whether they slept during the day or night.
The authors point out that their study needs to be repeated in larger studies and with other doses of melatonin to see if a dose between 0.3 and 5 mg can also work. The study did not include participants who had a significant sleep disorder, and the study results may not be applicable to people who have one.
“It’s exciting to see evidence that melatonin may have an impact on nocturnal sleep in older adults, knowing that so many older people have sleep disorders,” said lead author Jeanne Duffy, MBA, PhD, of the Department of Sleep and circadian disorders. “But before taking any supplement, it’s important that people talk to their GP and get referred to a sleep specialist to rule out an undiagnosed sleep disorder.”
Reference: “High-dose melatonin increases sleep duration during nocturnal and daytime sleep episodes in older adults” by Jeanne F. Duffy, Wei Wang, Joseph M. Ronda, and Charles A. Czeisler, April 18, 2022 The Journal of Pineal Research.
Funding: This work was supported by the National Institutes of Health (Grants P01 AG09975, AG06072, and AG044416), the Brigham and Women’s Hospital BRI Fund to Sustain Research Excellence, and was conducted at the Brigham and Women’s Hospital General Clinical Research Center (supported by M01 RR02635) .
Disclosures: Czeisler is/was a paid counsel to Physician’s Seal, Tencent Holdings, and Teva Pharma, and is a paid counsel and holds an equity interest in With Deep and Vanda Pharmaceuticals Inc., is/was an expert witness on legal matters, including those involving Vanda Pharmaceuticals involved; serves as the holder of an endowed professorship made available to Harvard University by Cephalon, Inc., which was acquired by Teva Pharma; and receives royalties from Philips Respironics for the Actiwatch-2 and Actiwatch Spectrum devices.