Jetlag has, literally, ZERO to do with the discussion. Jetlag is having to adapt suddenly to a change in the timezone which causes you to go to sleep earlier or stay awak longer for a single day. Then you suddenly resume what seems like a normal routine only to be thrust into a new one after the return trip.
Our bodies weren't "designed" to work this way. They evolved to work during the day. Also, I'm not sure where you're getting this bit about hormones and metabolism, study after study has shown that metabolic rate is not fixed, and that it adapts. You'll have to support this.
Stress related disease are also more prevailant among certain races more than others. Obviously, humans were not designed to be those races.
AM = morning. 12am (midnight) until 11:59am.
PM = night. 12pm(noon) until 11:59pm.
<{POST_SNAPBACK}>
oh ..thanks :"> I should have known this..i think i had, just have it forgotten :D