OTC Insomnia Supplements: The Latest Evidence

Darren J. Hein, PharmD


March 15, 2019


Dietary supplements are used by millions of people seeking a good night's sleep, but which ones are safe and effective?

Response from Darren J. Hein, PharmD
Assistant Professor, Department of Pharmacy Practice; School of Pharmacy and Health Professions, Creighton University, Omaha, Nebraska

As many as half of all people experience sleep problems at some point in their lives,[1] and equal numbers say that they frequently use dietary supplements.[2] So it is really no surprise that questions about the use of dietary supplements for insomnia are routinely fielded by clinicians.[3]

Even though effective prescription drug products are available for the treatment of insomnia, for many patients, barriers to access (eg, cost of office visit and prescription), as well as the serious and sometimes bizarre side effects associated with the use of these prescription drugs, make turning to dietary supplements an attractive option. The American Academy of Sleep Medicine reviewed some of the more popular supplement sleep aids (melatonin, L-tryptophan, and valerian), ultimately recommending against all three in the most recent clinical practice guidelines.[4] It is vital that clinicians be informed about the safety and efficacy of these sleep aids to appropriately counsel patients.


Melatonin, one of the most popular dietary supplements, is widely believed to help patients fall asleep faster and without significant safety concerns. But does the available clinical evidence support that?

Most research to date has been of low to moderate quality, despite melatonin being commonly studied for the treatment of insomnia. Analyses of clinical trials suggest that it decreases the time it takes to fall asleep (sleep latency) by 5-9 minutes,[4,5,6] and that patients with delayed sleep phase syndrome seem to fall asleep even faster.[5] These results represent a statistically significant improvement compared with placebo; thus, the clinical impact of melatonin's impact on sleep latency may be more profound when considering both the placebo effect and melatonin's observed improvement over placebo. This is also where patient preferences and values should be taken into consideration. For some patients, falling asleep a few minutes faster might greatly improve both quality of sleep and quality of life; for others, not so much.

What risks are associated with melatonin? Most studies show that melatonin's side-effect profile is comparable to placebo's. Additionally, melatonin does not appear to cause hangover or withdrawal symptoms, which are often reported with prescription drugs. A recent systematic review of adverse effects related to melatonin use confirms that the supplement is generally benign. The most concerning adverse effects include fatigue and impaired cognitive and motor function, but these were primarily observed when patients took melatonin during daytime hours or prior to cognitive or neuromotor tests.[7] Patients who choose to use melatonin for sleep should be instructed to take it only before bedtime to avoid these unwanted effects.


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