Melatonin is a naturally occurring hormone found in most animals, including humans, and some other living organisms. I n humans, melatonin is produced by the pineal gland, a gland about the size of a pea, located in the center of the brain. During the day, the pineal is inactive. When it becomes dark, the pineal is "turned on" by an area of the brain called the supra-chiasmatic nucleus (SCN) and begins to actively produce melatonin, which is released into the blood. Usually, this occurs around 9 pm. As a result, melatonin levels in the blood rise sharply and you begin to feel less alert. Melatonin levels in the blood normally stay elevated throughout the night, then with daylight they fall back to daytime levels (which can barely be detected).
Products containing melatonin have been available as a dietary supplement in the United States since 1993, although over-the-counter sales of melatonin are illegal in many other countries. But can melatonin supplements actually help you sleep better? And are melatonin supplements safe. According to MedlinePlus, (a service of the National Library of Medicine and the National Institutes of Health), there are five uses of melatonin for which there is either good or strong scientific evidence. The first of these is for treatment of jet lag:
“Several human trials suggest that melatonin taken by mouth, started on the day of travel (close to the target bedtime at the destination) and continued for several days, reduces the number of days required to establish a normal sleep pattern, diminishes the time it takes to fall asleep ("sleep latency"), improves alertness, and reduces daytime fatigue. Although these results are compelling, the majority of studies have had problems with their designs and reporting, and some trials have not found benefits. Overall, the scientific evidence does suggest benefits of melatonin in up to half of people who take it for jet-lag. More trials are needed to confirm these findings, to determine optimal dosing, and to evaluate use in combination with prescription sleep aids.”
One such study published in the Mar. 18, 1989, British Medical Journal reported that taking synthetic melatonin tablets can help travelers restore normal sleeping patterns. In that study, 20 volunteers traveling back and forth between New Zealand and England took daily doses of either 5 milligrams of melatonin or a placebo (a blank, or sugar pill) before, during, and after their flights. Those taking melatonin returned to their normal sleep patterns in 2.85 days on average compared with 4.15 days for those taking a placebo. And in 2005, MIT released the results of a meta-analysis of 17 peer-reviewed studies using melatonin. It showed that melatonin was effective in helping people fall asleep at doses of 0.3 milligrams (mg). Larger doses of melatonin seem to be less effective after only a few days' use.
The second use is for delayed sleep phase syndrome (DSPS), also known as delayed sleep-phase disorder (DSPD) or delayed sleep-phase type (DSPT). According to the International Classification of Sleep Disorders (ICSD), diagnostic criteria for Delayed Sleep-Phase Syndrome are:
1. There is an intractable delay in the phase of the major sleep period in relation to the desired clock time, as evidenced by a chronic or recurrent complaint of inability to fall asleep at a desired conventional clock time together with the inability to awaken at a desired and socially acceptable time.
2. When not required to maintain a strict schedule, patients will exhibit normal sleep quality and duration for their age and maintain a delayed, but stable, phase of entrainment to local time.
3. Patients have little or no reported difficulty in maintaining sleep once sleep has begun.
4. Patients have a relatively severe to absolute inability to advance the sleep phase to earlier hours by enforcing conventional sleep and wake times.
5. Sleep-wake logs and/or actigraphy monitoring for at least two weeks document a consistent habitual pattern of sleep onsets, usually later than 2 a.m., and lengthy sleeps.
6. Occasional noncircadian days may occur (i.e., sleep is "skipped" for an entire day and night plus some portion of the following day), followed by a sleep period lasting 12 to 18 hours.
7. The symptoms do not meet the criteria for any other sleep disorder causing inability to initiate sleep or excessive sleepiness.
8. If any of the following laboratory methods is used, it must demonstrate a delay in the timing of the habitual sleep period: 1) Twenty-four-hour polysomnographic monitoring (or by means of two consecutive nights of polysomnography and an intervening multiple sleep latency test), 2) Continuous temperature monitoring showing that the time of the absolute temperature nadir is delayed into the second half of the habitual (delayed) sleep episode.
Although there are studies suggesting the use of melatonin for DSPS is promising, additional research with larger studies is needed before a stronger recommendation can be made.
The third use is for insomnia in the elderly:
“Several human studies report that melatonin taken by mouth before bedtime decreases the amount of time it takes to fall asleep ("sleep latency") in elderly individuals with insomnia. Improved sleep quality and morning alertness has also been reported. However, most studies have not been high quality in their designs and some research has found limited or no benefits. The majority of trials have been brief in duration (several days long), and long-term effects are not known.”
The fourth is sleep disturbances in children with neuro-psychiatric disorders:
“There are multiple trials investigating melatonin use in children with various neuro-psychiatric disorders, including mental retardation, autism, psychiatric disorders, visual impairment, or epilepsy. Studies have demonstrated reduced time to fall asleep (sleep latency) and increased sleep duration. Well-designed controlled trials in select patient populations are needed before a stronger or more specific recommendation can be made.”
In April of this year (2009) the study "The Efficacy of Melatonin for Sleep Problems in Children with Autism, Fragile X Syndrome, or Autism and Fragile X Syndrome" published in the Journal of Clinical Sleep Medicine suggests that melatonin may help children with autism or Fragile X syndrome sleep, decreasing the length of time it takes for these children to fall asleep, and increase the amount of time they slept. According to the senior author, Beth L. Goodlin-Jones, PhD of the M.I.N.D Institute at the University of California Davis Health System in Sacramento, Calif., treatment with over-the-counter melatonin supplements benefits children of all ages, which helps alleviate some of the additional stress that parents of special-needs children experience.
The final use is for sleep enhancement in healthy people:
“Multiple human studies have measured the effects of melatonin supplements on sleep in healthy individuals. A wide range of doses has been used often taken by mouth 30 to 60 minutes prior to sleep time. Most trials have been small, brief in duration, and have not been rigorously designed or reported. However, the weight of scientific evidence does suggest that melatonin decreases the time it takes to fall asleep ("sleep latency"), increases the feeling of "sleepiness," and may increase the duration of sleep. Better research is needed in this area.”
When taking melatonin supplements, it’s important to remember that it’s not categorized as a drug. Because of this, synthetic melatonin is made in factories that aren’t regulated by the FDA, so listed doses may not be controlled or accurate, and the amount of melatonin in a pill you take may not be the amount listed on the package. According to the National Sleep Foundation, most commercial products are offered at dosages that cause melatonin levels in the blood to rise to much higher levels than are naturally produced in the body. Taking a typical dose (1 to 3 mg) may elevate your blood melatonin levels to 1 to 20 times normal. Side effects do not have to be listed on the product's packaging.
In our next post, we’ll look at melatonin’s potential side effects.