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morning use or high doses, and irregular wake-sleep cycles, disorientation, vision,
sleepwalking, vivid dreams, and nightmares are all possible side effects. Difficulties with
walking and balance may occur following overdose.
Case reports raise concerns about risks of blood clotting abnormalities, increased risk of
seizure, and disorientation with overdose.
Berkeley Wellness warns that “chronic” (long-term) use of melatonin supplements may
suppress the body’s own melatonin production and can interact with other hormones.
Therefore, pregnant women and children should never take melatonin. Berkeley also
lists high blood sugar, breast swelling in men, decreased sperm count, gastrointestinal
irritation, sleepwalking, the morning hangover effect (drowsiness in the morning) and
dizziness as potential side effects. For some people, melatonin may cause dozing off but
not staying asleep.
There is controversy about the effect of melatonin on seizure disorders. In the absence
of better science, consultation with the health care professional providing care for the
seizure disorder is essential while using melatonin.
Mood changes have been reported, both highs and lows (depression), and even
psychotic symptoms such as hallucinations and paranoia. Persons with severe
depression or psychotic disorders should consult with the health care professional
providing care for the underlying disorder before using melatonin.
Since melatonin may cause adverse changes in blood pressure and cholesterol levels,
caution is advised to persons with or at risk of cardiovascular disease. Abnormal heart
rhythms have been reported.
Melatonin may increase blood sugar levels for people with type 1 diabetes and may
lower them in type 2 diabetes. Anyone with diabetes should monitor blood sugar levels
while using melatonin.
Hormonal effects are to be expected with the use of an estrogen-like hormone. These
effects include decreases or increases in levels of luteinizing hormone, progesterone,
estradiol, thyroid hormone, growth hormone, prolactin, cortisol, oxytocin, and