Melatonin is a hormone secreted by the pineal gland in the brain, with lesser amounts produced in the retina and gastrointestinal tract. Its principal function is to regulate sleeping patterns and to maintain the body’s internal 24-hour circadian rhythm. Darkness stimulates the formation of this hormone and exposure to light, either natural or artificial, suppresses production.
Normal melatonin production is jeopardized by excessive light stimulation caused by artificial light. Shift workers in particular are prone to irregularities in melatonin secretion, often experiencing difficulties in sleep/wake patterns. Traveling across time zones, resulting in the discomfort of jetlag, is another well-known symptom of melatonin disturbance. There is also growing evidence that exposure to low frequency electromagnetic radiation, such as is emitted by common household appliances like digital clocks, refrigerators, and computers, may also have a detrimental effect on the body’s melatonin supply.
Melatonin is also instrumental in determining the timing of menstruation, the frequency and duration of menstrual cycles, and the commencement of menopause. Children have much higher levels of melatonin than adults, with production levels being found to decrease with age. This may explain why the elderly sleep less than their younger counterparts and experience greater difficulty in falling asleep.
Supplementation with melatonin has been found to be superior to the placebo effect in treating insomnia. It reduces the time needed to fall asleep, lengthens total sleeping time, and increases daytime alertness. Jetlag also responds well to melatonin supplementation, particularly for east-west movement across several time zones.
Melatonin also appears to be beneficial in the treatment of osteoporosis, having been found in laboratory studies to promote bone growth. Depression has been linked to low levels of melatonin, with sufferers reporting improved sleep patterns as a result of short-term use. Low levels of melatonin production have also been recorded in women suffering from breast cancer, as well as in men exhibiting symptoms of prostate cancer. There is limited, yet encouraging, evidence that supplementation with melatonin, in conjunction with traditional cancer treatment, assists in promoting survival rates for these two common types of cancer.
Preliminary investigations into the effect of melatonin on rheumatoid arthritis suggest that melatonin mimics the effect of anti-inflammatory medications due to its similar biochemical structure. Further research is required in this area.
Few side effects of melatonin have been reported but include drowsiness, particularly if taken during the day. Infrequent occurrences of vivid dreams, stomach upsets, headache, irritability, and dizziness have been reported. Melatonin supplements should not be taken by pregnant or nursing mothers. Individuals on antidepressant, antipsychotic, and antianxiety medications should consult their healthcare provider before commencing treatment.