The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature

Abstract: A systematic review was conducted using Samueli Institute’s Rapid Evidence Assessment of the Literature (REAL©) process to determine the evidence base for melatonin as an agent to optimize sleep or improve sleep quality, and generalize the results to a military, civilian, or other healthy, active, adult population. Multiple databases were searched yielding 35 randomized controlled trials (RCTs) meeting the review’s inclusion criteria, which were assessed for methodological quality as well as for melatonin effectiveness. The majority of included studies were high quality (83.0%). Overall, according to Grading Recommendations, Assessment Development and Evaluation (GRADE) methodology, weak recommendations were made for preventing phase shifts from jet lag, for improving insomnia in both healthy volunteers and individuals with a history of insomnia, and for initiating sleep and/or improving sleep efficacy. Based on the literature to date, no recommendations for use in shift workers or to improve hormonal phase shift changes in healthy people can be made at this time. Larger and longer-duration RCTs utilizing well characterized products are needed to warrant melatonin recommendations in young, healthy adults.

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Alex’s Notes: I had a good laugh when I noticed that the authors were from the military. While the current study was indeed a systemic review, leave it to the military to find a way to streamline the process. This review utilized the Rapid Evidence Assessment of the Literature (REAL) process, which differs from a traditional systemic review in that it does not “exhaustively” search the literature, but rather includes only randomized controlled trials to provide a snapshot and come to a similar bottom line. The authors had four goals in mind,

  1. Determine the evidence base for melatonin to optimize sleep (e.g., improve sleep quality, duration, ability to fall asleep);
  2. Evaluate the safety of melatonin use;
  3. Assess outcomes and dosing structure most applicable for this research; and
  4. Generalize results to those who suffer from issues related to sleep disturbances and sleep hygiene.

With these goals in mind, the articles were restricted to healthy populations, or populations diagnosed with insomnia, as that is a common side-effect of being in the military.Ultimately, 35 RCTs with a total of 2,356 subjects were included in this review. To stay true to the streamlined process, I’m going to skip much of the filler talk (needless to say the military is also efficient and did a really good job of covering every aspect of every study).

The authors investigated the use of melatonin in healthy populations across various sleep behaviors, and divided the included studies into four distinct user groups: shift workers, individuals experiencing jet lag, persons suffering from insomnia, and healthy individuals who want to improve their sleep. Overall, results suggest that melatonin shows promise to prevent phase shifts from jet lag, improve insomnia in otherwise healthy adults, albeit to a limited extent, and the evidence for shift workers is inconclusive.

When looking to healthy persons in need of improved sleep, melatonin may help with initiating sleep or sleep efficacy and alleviating daytime sleepiness or somnolence, but no conclusions regarding melatonin’s effects on producing phase shifts or hormone changes could be made. Although no serious adverse events or health risks from melatonin use were noted, daytime administration (0.1 to 1.0 mg) produced significant drowsiness, fatigue, and performance decrements, which appear to peak approximately three to four hours after ingestion. Moreover, the authors note that melatonin has been shown to reduce body temperature, which could preclude its use under conditions of cold stress.

So is melatonin military ready? According to the authors it may be worth a shot,

“Melatonin in a wide array of preparations and amounts demonstrates few significant and limiting adverse events. Because melatonin has a very low side effect profile and limited evidence of habituation and tolerance, its use in Service Members could be considered for specific tasks.”


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