Physiology of Melatonin
Melatonin is produced by a gland located in the brain known as the pineal gland. This hormone is produced at high levels during a persons normal sleeping hours and decreases during the day. It has been found that elderly patients who suffer from insomnia have lower blood levels of melatonin. Interestingly, blind people have a constant production of melatonin since the day and night variation of melatonin is thought to be influenced by exposure of the eyes to light and thus influencing the production of melatonin by the pineal gland. Not surprisingly, blind people tend to have irregular sleep patterns since they do not have the visual stimulation from light. In one study, it was found that giving blind persons melatonin before their desired bedtime helped to relieve insomnia.Commercial Production of Melatonin
Melatonin is sold by its various manufacturers as a dietary supplement and therefore does not come under the regulation of the Food and Drug Administration. Producers of melatonin do not have to give proof of purity or demonstrate that there is any melatonin in their product. Producers of melatonin have refused to disclose to The Medical Letter the source of the melatonin, but it was speculated that it was derived either from cow pineal glands or that it was produced chemically. A consultant for The Medical Letter analyzed several samples of melatonin from health food stores and found they contained chemical impurities that he could not identify.
Jet Lag
Several studies were done to see if jet passengers were less likely to develop jet lag after administration of melatonin slightly before their usual bedtime. When compared to the placebo group (sugar pill), the melatonin group usually experienced less symptoms of jet lag. The melatonin was generally taken five days prior to travel and then taken another five days upon arrival.
Induction of Sleep Multiple studies using melatonin as a sleep aid in both insomniacs and normal volunteers have generally shown that melatonin to be modestly effective. One study of insomniacs found that when melatonin was administered two hours before bedtime that the time needed to fall asleep decreased by fourteen minutes, decreased time awake after falling asleep by twenty four minutes, but did not prolong total sleep time. None of the studies examined reported any adverse effects from the melatonin.Recommendations
I would echo the conclusions given by The Medical Letter: melatonin may be an effective aid for sleep and may decrease the effects of jet lag, but the studies were small in size and short in duration. The most worrisome aspect of melatonin is the unregulated production of melatonin by health food stores raising concerns regarding potency and purity of the melatonin. It was also pointed out that the long term effects of using melatonin are completely unknown. If one is confident about the quality of the source of melatonin, it could be a useful sleep aid.
Lloyd Ito, MD11/30/03