The science of jet lag --and how to help cope when you travel, from LiveScience:
--It's harder to adjust when you fly east. That's because of a small quirk in your body's cells that control the biological clock --also known as the your circadian rhythm: These cells operate on daily cycle of 24.5 hours. A small difference from 24 hours, but big enough that flying east across time zones shortens your day while your cells are operating on a longer day.
--The direction you're traveling affects how long you need to recover: When traveling west, it should take most people a little less than four days to recover from crossing three time zones and just under eight days for crossing nine time zones.
--When traveling east, you need longer adjustment periods. You need little MORE than four days to recover from crossing three time zones, and more than 12 days for crossing nine time zones.
--Exposure to bright light early in the morning can help you recover faster. Researchers are investigating the possibility of developing jet lag-recuperating eye drops. It's also possible that small shifts in oxygen levels could help ease the jet lag transition.
--Flying isn't the only thing that causes jet lag. Changes in your social schedule, even when you stay at home can cause "social jet lag" --that's anything that can cause your body's internal clock to fall out of sync. If you keep a different schedule on weekdays compared with the weekend, you've probably experienced this. --Jet lag doesn't just mess with you when you fall asleep and when you wake up --it can also affect essential body functions like controlling blood sugar levels. Changing your meal time could help you adjust to different time zone or work schedule.