Says Dr C. V. Krishnan, Consultant Endocrinologist, Apollo Hospital, Chennai: ``Melatonin is very effective as an anti-oxidant and is used in treating the toxic effects of chemotherapy. It is also boosts the immune system, which makes it a useful drug in treating immune disorders like AIDS.'' Melatonin is especially effective in the polluted city environs because of its anti-toxicity properties.

Marketed in India for Rs 3,500 for a 100 ml bottle and Rs 4 for a capsule, melatonin is being lapped up, predictably, for all the wrong reasons. ``I prescribed melatonin to a patient who suffered from severe migraines. She came back a few weeks later saying that she was more than happy with the medicine, though her migraines had not gone completely. It turned out that she was thrilled because many people had told her that she had become much fairer,'' says Krishnan.

Melatonin levels in the body come down drastically during the day, at times about 10 times less than the peak levels at night. Since the hormone is most effective at night, doctors still advise you to take melatonin doses at night. ``The tablets have a half-life of 45 minutes, that is, it is most effective 45 minutes after it is taken, after which the effect starts waning. The solution, on the other hand, peaks after eight hours. If it applied at night, it will work while you sleep,'' says Krishnan. Pregnant women and those with liver diseases should avoid taking melatonin orally, but the lotion can be applied by all. If allergies are reported at all, they can be combatted by decreasing the dosage.

Krishnan has more reason to be happy with melatonin. ``My daughter is dyslexic and could not carry on a telephone conversation two months ago. After two months of treatment, the change is dramatic and she can intelligently take messages,'' he says. Reason enough for him to sing the virtues of melatonin.