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Although melatonin has, in some ways, become synonymous with sleep, other clinical approaches would serve as first-line interventions before using melatonin. Dysfunctional sleep does not have one mechanism, such as reduced melatonin, but potentially several causes, some or all, may be impacting melatonin levels. With over eighty sleep disorders (1), full assessment and diagnosis are important for effective treatment. Underlying inflammation-related diseases may need to be addressed, such as metabolic syndrome, sleep apnea, and any type of joint or muscle pain (2,3). Even hormonal fluxes related to estrogen, cortisol, and insulin are essential to assess for imbalance and correct accordingly (4–6). Moreover, there may be an association between environmental toxins such as heavy metals (e.g., arsenic) and sleep disturbance (7,8). Sleep hygiene, such as room temperature, adequate darkness, noise, and comfort of bed and pillows, would be simple actions to ensure a healthy environment (9,10). Further to the sleeping room, engaging in healthy lifestyle practices such as refraining from stimulants, eating or being on devices too close to bedtime, and unwinding from the day’s stresses with relaxation practices such as a warm bath or physical activity, need consideration (11,12). From a nutritional standpoint, assessing dietary intake of macronutrients, especially tryptophan-containing sources of protein (12), along with micronutrients such as magnesium (13), vitamin D, and calcium, would be essential for ensuring a biochemical foundation that would foster healthy sleep (14). Thus, melatonin would be utilized preferentially when the other changes have been implemented if there was an indication.


Melatonin has a hypothermic action. A decrease in core body temperature is soporific (15). In this way, exogenous melatonin can have a direct effect on sleep. A meta-analysis of melatonin for the treatment of primary sleep disorders analyzed nineteen studies involving 1683 individuals. Melatonin had a statistically significant effect on reducing sleep latency and increasing total sleep time. Trials that used higher doses of melatonin and conducted over a longer duration demonstrated even greater effects on these two sleep issues, and overall sleep quality was also significantly improved in melatonin users (16,17).


A 2017 systematic review (18) identified 5030 studies on melatonin and sleep, but only twelve were included to meet their criteria for randomized, controlled, and single or double-blind studies. The summary concluded that melatonin is indicated for the following (18):

  • Insomnia: Immediate release 1–3 mg, <30 min before bed; slow-release can be used for sleep maintenance problems

  • Regulating sleep in blind individuals who often experience non-24 h sleep-wake rhythm disorder;

  • Replicating the normal endogenous pattern;

  • Delayed sleep phase.


In 2022, researchers at Harvard Medical School and Brigham and Women’s Hospital explored low (0.3 mg) and high (5 mg) dose melatonin in a relatively small sample of healthy older adults. Both doses improved sleep efficiency, but the higher dose impacted the biological day and night sleep patterns, the duration of non-REM sleep, and awakening time (19).


Melatonin supplementation has shown promise in a rare sleep disorder, idiopathic REM Behavior Disorder (iRBD). Patients with iRBD will retain muscle tone during REM sleep and can act out their dreams, posing a danger to themselves and others. Importantly, iRBD is a prodrome biomarker for Parkinson’s disease. In one study, six months of low-dose 2 mg melatonin supplementation taken at the same clock time (between 10–11 pm, personalized to the individual’s chronotype) resulted in a decrease in iRBD symptom severity over the first four weeks of treatment. This improvement was maintained over the follow-up period of 4.2 +/− 3.1 years (20).


Authors: Deanna Minich, Ph.D., Melanie Henning, ND, Catherine Darley, ND, Mona Fahoum, ND, Corey B. Schuler, DC, James Frame

Reviewer: Peer-review in Nutrients Journal

Last updated: September 22, 2022



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