Melatonin Central, on the Internet, notes a number of adverse side-effects. Melatonin from a natural source may be derived from cattle. Synthetic melatonin is less worrying, the doctors say. But many add that even in normal, healthy adults, melatonin use can result in some minor side-effects. Nausea, disorientation, dizziness, nightmares, headaches and, oddly enough, wakefulness have been reported.
Most users take the product just before they intend to fall asleep.
This is why, around ten o'clock, most people begin to feel drowsy. Permanent damage, though reported only anecdotally, is also possible. This could mean an end to natural, regular sleep. To some extent, melatonin's popularity in Asia is understandable. Most bottles carry the warning that children and pregnant women should not take melatonin.