The recommendation to start taking melatonin 1-2 days before travel is the "old" guideline, and the new being as above 3 to 5 not .5 (half)mg at local bedtime traveling east or west.

There are more complicated tables available as johna said, basically the dosing time changes by an hour earlier or later depending on either east- or west- bound travel. These tables are more helpful for certain groups of travellers that need more stringent day-night cycle control; but for the layperson the easy, simple just take it at local bedtime is good, and people tend to be more compliant with easier regimens.

[This message has been edited by burkey (edited 06-18-1999).]