A quick primer on melatonin

Melatonin is a very popular dietary supplement to improve sleep. It is also a hormone secreted by the pineal gland, a small pea-sized gland at the base of the brain. The exact function of melatonin is still poorly understood, but it is critically involved in regulating the natural biorhythm of hormone secretion referred to as the “circadian” rhythm,” as well as controlling sleep/wake cycles.

Release of melatonin is stimulated by darkness and suppressed by light. The primary uses of melatonin as a dietary supplement are as a natural sleep aid, and also as an aid for jet lag. It has also shown promise in a few other areas.



Melatonin plays an important role in the induction of sleep. Low melatonin secretion at night can be a cause of insomnia, particularly in the elderly. Several double-blind trials have shown melatonin supplementation to be very effective in promoting sleep, but it appears the sleep-promoting effects of melatonin are most apparent when melatonin levels are low. Low melatonin levels are thought to be an extremely common cause of insomnia in the elderly, while in younger individuals it is less of a factor.


Melatonin and methylcobalamin in sleep-wake disorder

Sleep-wake disorder is characterized by excessive daytime sleepiness, restless nights, and frequent nighttime awakenings. It is very common in shift workers and the elderly. Melatonin combined with a special vitamin B12, methylcobalamin, can be very effective in improving sleep-wake disorder.

Taking 3 mg of methylcobalamin sublingually first thing in the morning can lead to improved sleep quality, increased daytime alertness and concentration, and improved mood in people with sleep-wake disorder both in elderly and young subjects. Much of the benefit appears to be a result of methylcobalamin influencing melatonin secretion—taking it in the morning shuts down daytime melatonin allowing for an increase of nighttime secretion.

Low levels of melatonin in the elderly may be a result of low vitamin B12 status. As a further aid to reset the sleep-wake cycle, melatonin (3 mg) can be taken 30 to 45 minutes before bedtime.



Children with autism spectrum disorder (ASD) often experience problems with getting to sleep, as well as with sleep maintenance. The consequences of this poor sleep quality may include alterations in daytime behavior, memory and learning. One of the possible reasons for sleep issues is a disturbance in the manufacture of melatonin.

Several clinical studies have also shown that melatonin supplementation at dosages ranging from 0.75 mg to 6 mg prior to bedtime produces significant benefit in improving sleep quality in ASD.

In one study, 86 percent of parents of autistic children reported either complete elimination or significant improvement of sleep disturbance with melatonin supplementation. Of the 107 children treated with melatonin, only three children had mild side effects (morning sleepiness).


Jet lag

Several double-blind studies have shown melatonin to be very effective in relieving jet lag. Different dosage recommendations have been given. It appears the best results are achieved when melatonin is taken at a dosage of 5 mg in the evening at the new destination for five days.


Anti-aging effects

Melatonin has been shown to possess antioxidant and longevity-promoting effects in animal studies. For example, in studies in rats, melatonin supplementation leads to significantly longer lives (31 months vs. 25 months).

There are a lot of possible explanations for melatonin’s anti-aging effects, however, the primary effect may be simply by acting to help improve sleep quality. Poor sleep quality at any age triggers the stress response and leads to an increase in inflammation, which is more problematic as we get older. Inadequate sleep or poor sleep quality accelerates the aging process, especially in the brain. Not surprisingly, melatonin supplementation has been shown to slow down the aging process in the brain in experimental studies.

Melatonin helps other body tissues as well through improving sleep quality. For example, poor sleep quality leads to an increase in the activity of the cells that break down bone (osteoclasts). The thought is because melatonin can help improve sleep quality, it may also help prevent excessive bone breakdown.


Usual dosage

In the treatment of insomnia, a dosage of 3 mg at bedtime is the most common recommendation. This dosage appears to be more than enough as dosages as low as 0.1 mg and 0.3 mg have been shown to produce a sedative effect in individuals with low melatonin levels.

Higher dosages (e.g., 5 mg) have been used in some sleep studies, but overall effects do not appear to be more significant than seen at 3 mg. The dosage for jet lag is 5 mg in the evening at the new destination for five days.

Melatonin is most often available as a sublingual or chewable tablet. Timed-released preparations designed to replicate the body’s own melatonin secretion may provide the best results in treating insomnia.


Possible side effects and concerns

Melatonin is generally very well tolerated with no apparent symptoms. Morning sleepiness may be an issue for some.

Although there appear to be no serious side effects at recommended dosages, conceivably melatonin supplementation above 8 mg daily could disrupt the normal circadian rhythm and lead to changes in the levels of key body hormones.

Melatonin may enhance the anti-cancer effects of certain chemotherapy agents. Specifically, in human studies, melatonin has been shown to enhance the anti-cancer effects of chemotherapy drugs, such as interleukin-2, interferon, and tamoxifen. This may be a beneficial effect in people taking these drugs.

Melatonin has been found to be helpful in treating withdrawal reactions from people addicted to benzodiazepine drugs (i.e., tranquilizers like Valium and Halcion). Melatonin levels are typically lowered by beta-blocker drugs like Inderal and Atenolol, as well as by other drugs used in treating high blood pressure or angina (e.g., verapramil).


Final comments

There are two common questions regarding melatonin. First, can melatonin be used during pregnancy and lactation. Here is the standard response: as the effects of melatonin during pregnancy and lactation have not been sufficiently evaluated, it should not be used during these times.

Second question. Can melatonin be used in children? It seems safe, though the standard answer is since we don’t know definitively, say “no” and suggest consulting a medical professional. For me, melatonin would not be the first choice in a child who was not sleeping well. In terms of natural sleep aids for use in children, I would go with either L-theanine or natural GABA. The exception would be in children with confirmed low melatonin secretion or in children with autism. VR

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