What is melatonin? Melatonin is a hormone produced by the pineal gland (a tiny gland in the brain) that helps regulate the sleep-wake cycle. Production of melatonin generally increases as darkness increases, which in turn, helps make us sleepy as night approaches. Production is generally suppressed by light, so we tend to be more awake during the day. That cycle of sleepy and wakeful is referred to as our circadian rhythm.
How does melatonin work? By signaling the body that it’s time to sleep, the thought is that it may help with insomnia or delayed sleep phase disorder (trouble falling asleep before 2 AM) as well as shift work disorder (those who work night shifts) and jet lag. That being said, studies have shown mixed results with regards to efficacy. Perhaps for those who are truly deficient, they may see more improvement of symptoms than those who are able to produce adequate amounts on their own, but for now, there doesn’t seem to be a way to determine which individuals would be most responsive to supplemental melatonin.
Is melatonin safe? Generally, melatonin is considered relatively safe for short term use, i.e. 1-2 months, although long term safety information is limited. There are certainly those who should avoid melatonin use such as those on blood thinners, diabetes medications, immunosuppressants, dementia medications, and even birth control pills because melatonin can affect the efficacy of these medications. Also, use in children should be discussed with a pediatrician as there is a question of whether or not melatonin, as a hormone, can affect hormonal regulation of growth and even puberty or menstrual cycles in those with immature endocrine systems. As for those who are pregnant or breastfeeding, there is no quality data regarding safety for use of melatonin. Common side effects can include daytime sleepiness, anxiety, GI distress, dizziness and depression among others. Because it is considered a supplement in the U.S. (rather than a drug, which would be managed by the FDA), safety and efficacy data is limited. In fact, a study of melatonin supplements from a few years ago showed that the amount of melatonin listed on the bottle varied significantly from the amount actually in the product in most of those products evaluated, and around a quarter were contaminated by serotonin.
In the end, reviews of safety and efficacy are mixed for supplemental melatonin. The American College of Physicians recommends cognitive behavioral therapy as a first-line treatment of insomnia. As for simple changes to make on your own, limiting daytime naps, having consistent bedtimes and wake times, exercising regularly and avoiding electronics (especially those emitting blue light) for several hours before trying to sleep can all be good places to start. Often, the hardest part of making these changes is avoiding the temptation to catch up on some missed sleep at night with naps during the day, but by being more tired when trying to fall asleep at night, resuming (or starting) a more regular sleep schedule can be within reach.