Melatonin is an extensively researched and widely used supplement for a variety of sleep disorders. Although available synthetically as a supplement, melatonin is a naturally occurring hormone secreted by the pineal gland in the brain. Synthesis of melatonin is regulated by external cues of light and darkness. The University of Maryland Medical Center (UMMC) reports that melatonin helps to regulate other naturally produced hormones and maintains the body's internal time-keeping system, known as the circadian rhythm.
The body's circadian rhythm functions as an endogenous 24-hour light-dark cycle and helps to regulate sleep patterns. Light suppresses the activity of melatonin, while darkness stimulates its synthesis. Secretion of melatonin is highest prior to bedtime, suggesting the involvement of melatonin in sleep regulation. Improper exposure to light, especially excessive light before bedtime, could lead to disruption of melatonin synthesis and sleep abnormalities. Persons who do shift work, have poor vision or suffer from jet lag may be more prone to diminished production of melatonin and disturbed sleep patterns. Additionally, UMMC reports that researchers believe there is a link between diminished levels of melatonin and disrupted sleep patterns in the elderly; thus melatonin-replacement therapy may be beneficial for sleep maintenance.
Strong Uses
MedlinePlus suggests several evidence-based uses for the supplement melatonin and gives each use a letter grade. Uses given the grade of "A" indicate that strong scientific evidence exists for use. The use of melatonin for jet lag is very effective, and MedlinePlus gave this use an "A." In persons interested in preventing jet lag, melatonin was found to improve sleep latency (the time it takes to fall asleep) and alertness, reducing daytime fatigue. Melatonin also proved helpful in reducing the number of days necessary to regain a normal sleep pattern.
Good Uses
Uses given a "B" by MedlinePlus indicate that good scientific evidence exists for use. Any use below the grade of "B" indicates unclear scientific evidence or evidence against melatonin for use. Uses given a "B" include delayed sleep phase syndrome, sleep disturbances in children with neuro-psychiatric disorders, insomnia in the elderly and sleep enhancement in healthy people. In persons with delayed sleep phase syndrome, melatonin was shown to reduce the delay of sleep onset. In children with neuro-psychiatric disorders, research has demonstrated an increase in the duration of sleep and a decrease in sleep latency. Melatonin has also been reported to decrease sleep latency in the elderly. While research is not conclusive, evidence indicates that melatonin decreases sleep latency, increases the duration of sleep and the feeling of "sleepiness" in healthy individuals.
Common Side Effects
The Mayo Clinic reports that melatonin is generally safe and effective in recommended doses for short-term use. More common side effects include dizziness, sleepiness, headache, irritability, nausea, vomiting and cramping. A "hangover" effect may occur in the morning hours from taking high doses of melatonin the night before, causing fatigue. Some people may also experience confusion, sleepwalking, nightmares and vivid dreams while taking this supplement. Risk of daytime sleepiness may increase while taking melatonin, so it is important to determine how your body responds to this supplement before driving or operating heavy machinery.
Additional Side Effects
Case-by-case reports of adverse reactions have been made in regard to blood clotting problems, increased risk of seizure and allergic skin reactions after consumption of melatonin by mouth. Some patients have reported changes in mood, including sadness, giddiness, hallucinations and paranoia. Patients with mood disorders, such as depression, should consult a medical care provider before taking this supplement. Patients with heart conditions and diabetes should also consult with a medical care provider prior to taking melatonin. Melatonin could cause changes in blood pressure, increases in cholesterol levels and elevation of blood glucose levels. Hormonal side effects have also been reported and are listed by the Mayo Clinic to include increases or decreases in levels of progesterone, luteinizing hormone, thyroid hormone (T4 and T3), growth hormone, estradiol, prolactin, cortisol, vasopressin and oxytocin. Some men have also reported decreased sperm count and sperm motility, as well as increased breast size. Talk with your medical care provider prior to taking melatonin to ensure that this supplement is safe for you.
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