1.   And scientists in Israel and Switzerland have found that when mice receive melatonin, their odds of surviving infection with an encephalitis virus more than double.

2.   Between the two experiments, of eight people who received melatonin at the determined biological moment, four had trouble sleeping.

3.   Half the animals received melatonin with the safrole.

4.   The two men who had trouble sleeping were, in effect, receiving melatonin at a different biological moment in their metabolic cycles.