In a small study in healthy adults aged 55 and older, 5 mg of melatonin increased total sleep time compared to placebo.
Although recent research by Cambridge University and Fudan University found that seven hours is the ideal length of sleep, many Americans receive less than that. In fact, CDC data from 2014 revealed that 35.2% of adults in the United States sleep less than 7 hours. Obviously, many of us could use some help to fall asleep faster and sleep better.
Melatonin is one of the most widely used supplements in the United States. Among the elderly, its use has tripled over the past two decades. But there’s no consensus on the right dosage of melatonin, and studies of its effects on sleep quality in older adults have had mixed results. Researchers at Brigham and Women’s Hospital conducted a study in 24 healthy older adults to assess whether a high- or low-dose melatonin supplement could improve sleep. The team found that the higher dose had a significant impact, increasing total sleep time compared to placebo by more than 15 minutes for nighttime sleep and half an hour for daytime sleep. The results are 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 synchronize your circadian rhythms (internal 24-hour clock) and control the sleep-wake cycle. Being exposed to light at night can block the production of melatonin.
“Sleep deprivation becomes more common as people age, and given the drawbacks of many prescription sleeping pills, many older people report taking melatonin,” said lead author Charles Czeisler, PhD, MD, chief of Brigham’s division of sleep and circadian disorders. “But we had little evidence on the effects of melatonin on sleep health in older people. Our study provides new evidence and insights, and underscores the importance of considering dosage and timing when it comes to the effects of supplements like melatonin, especially in older adults.
The body naturally produces the hormone melatonin, which helps regulate a person’s sleep-wake cycle with night and day. Melatonin levels peak at night. But in older people, levels of the hormone are often lower. Exogenous melatonin is available without a prescription and can be taken before bedtime as a dietary supplement, usually in 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 disturbances. All potential participants were screened for sleep disorders. The study included 24 participants (13 women, 11 men) aged 55 to 78.
During the month-long study period, participants lived in individual study rooms without windows, clocks, or other time-of-day cues. Participants followed a forced desynchronization protocol — instead of experiencing 24-hour cycles of days and nights, they followed 20-hour cycle schedules to unravel the effects of resting activity on the circadian clock. This allowed sleep to be scheduled for both night and day, but with a similar amount of wakefulness before each sleep. Participants were randomly assigned to receive two weeks of a placebo pill and two weeks of a low (0.3 mg) or high (5 mg) dose of melatonin 30 minutes before bedtime. The researchers used polysomnography to record brain waves, eye movements, muscle tone and other key measures of sleep.
The team found that the low dose of melatonin did not lead to a statistically significant change in overall sleep time and that the observed changes were in when sleep was scheduled during the biological day. Participants taking the 5mg dose had a significant increase in total sleep time and sleep efficiency, whether sleep was scheduled during the day or at night.
The authors note that their study will need to be replicated in larger trials and with other doses of melatonin to determine if a dose between 0.3 and 5 mg may also work. The study did not include participants with a significant sleep disorder, and the study results may not apply to people who do.
“It’s exciting to see evidence that melatonin may impact nighttime sleep in older adults, because we know so many older people have trouble sleeping,” said lead author Jeanne Duffy, MBA, PhD, from the Division of Sleep and Circadian Disorders. . “But before taking any dietary supplement, it’s important that people speak to their primary care physician and be 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 the Elderly” 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 M01RR02635).
Disclosures: Czeisler is/was a paid consultant for Physician’s Seal, Tencent Holdings and Teva Pharma, and is a paid consultant and has an equity interest in With Deep and Vanda Pharmaceuticals Inc., is/was an expert witness in court cases, including those involving Vanda Pharmaceuticals; holds the position of endowed chair provided to Harvard University by Cephalon, Inc., which was acquired by Teva Pharma; and receives royalties from Philips Respironics for Actiwatch-2 and Actiwatch Spectrum devices.
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