If you have trouble falling asleep or staying asleep, especially as a result of getting older, you might want to consider taking a melatonin supplement. Expounding on the ways in which melatonin can aid your sleep takes some scientific research to explain exactly how the biology of melatonin works and in what ways external (i.e. In a human in a “state of nature”—no artificial lights or rapid international travel—melatonin is reliably and consistently produced at the onset of darkness.
As a result, your blood melatonin levels go up when it gets dark out, and you become sleepy (1). Of course, things aren’t this simple with modern humans. We stay up late with artificial lights, and we often travel through many time zones, which can disrupt our body’s internal sleep and wake cycles. Some researchers hypothesize that this is why many elderly people suffer from insomnia (2). In all of these cases, modulating melatonin levels in your body via external intake from a supplement at the appropriate time of day is one way to correct this. For age-related insomnia, a 2001 study investigated whether melatonin supplementation can help. A team of researchers at the Massachusetts Institute of Technology examined sleep quality in fifteen subjects over 50 years old who had insomnia and poor sleep efficiency (3).
The researchers tested three doses of melatonin: 0.1 mg, 0.3 mg, and 3 mg, taken half an hour before bed every day for a week. The results showed that the best effects came from a fairly low dose: the 0.3 mg dosage improved sleep efficiency, especially in the middle of the night, and restored melatonin levels in the blood to their normal values. The 3 mg dose also improved sleep efficiency, but it caused blood levels of melatonin to remain elevated during the day, too. The researchers also noted that control subjects who did not have age-related insomnia did not experience any changes in sleep quality, even though they had low melatonin levels. It may be that some people’s bodies are able to adapt to lower physiological levels of melatonin and still get quality sleep; in these cases, a melatonin supplement probably is not necessary in these cases. Jet lag can strike when you cross numerous time zones while traveling. Petrie for the Cochrane Collaboration of systematic reviews looked at evidence from ten studies on melatonin for treating or preventing jet lag (4). The researchers found that melatonin was “highly effective” at treating and preventing jet lag, as long as you take it close to your target bedtime at your destination of arrival. The benefit is greater for trips that cross more time zones and for eastbound trips. Taking the melatonin supplement at the wrong time of day (i.e. not within half an hour or so of bedtime at your location of arrival) can disrupt your sleep schedule, causing drowsiness and worsening your jet lag instead of improving it. As many readers know, sleep can be disturbed even if you aren’t jet-lagged or reaching old age. Fortunately, melatonin can improve sleep quality in healthy adults, too. Sharpley at Littlemore Hospital in the United Kingdom described an experiment which examined the effects of a dose of melatonin on sleep quality in middle aged volunteers (5). The authors tested a 1 mg and 0.3 mg dose of melatonin before sleep, then studied the brain waves and eye movements of the subjects during their sleep. The subjects also underwent similar experiments using a placebo. In the case of the melatonin, the researchers found that the supplement caused an increase in total sleep time, an increase in non-REM sleep, and “sleep efficiency,” which is a measurement of how “good,” qualitatively speaking, your sleep is. Highly efficient sleep should leave you feeling alert and rested the following day. One of the real draws of melatonin is its very safe side effects profile. A large review of numerous studies on melatonin use found that its safety profile for short to medium-term use (a few weeks to a few months) was excellent (6); the only major side effect of note is sleepiness and grogginess when it is taken at the wrong time of day. Even in excessively high doses, melatonin seems to have no additional adverse effects.
Some case reports do caution against using melatonin if you have epilepsy or if you take warfarin or other blood thinners—in these cases, you should definitely talk to your doctor first before taking melatonin (7). Interestingly, melatonin appears to be effective at a wide range of doses. In the studies discussed above, doses of as little as 0.3 milligrams have been effective at improving sleep quality. The Cochrane review of studies on melatonin for jet lag noted that doses of 0.5 mg to 5 mg were equally effective in almost every respect. The only difference was that doses of 5 mg seem to induce sleep more rapidly than doses of 0.5 mg. Doses above 5 mg do not seem to have any additional benefits. Slow release doses appear to be more effective for insomnia, while jet lag is just the opposite: it appears that a short but steep increase in blood melatonin levels is all it takes to help reset your biological clock once. A slow release formula might be more appropriate for people who have issues staying asleep instead of falling asleep. A: Clinical research on sleep disorders and sleep disruption suggests that, for most people, the optimal dosage of melatonin is between 0.5 and 5 mg, taken all at once. Higher doses, like the 10 or 12 mg doses you’ll sometimes find in over the counter melatonin supplements, don’t seem to be any more effective at promoting any metric related to sleep compared to lower doses.
Within the recommended dosage range, the only difference has to do with how quickly you fall asleep. If you primarily have trouble staying asleep, but not falling asleep, or the sleep you get is not restful, the actual dosage of melatonin does not seem to matter very much, as long as it’s at least 0.5 mg.