Errr... thanks God you don't really want to know the answer to the 1st question 'coz I would need a dictionary to understand it!
About the jetlag and how to cope with it, mmhhh... well... I think everyone is different. My personal experience taught me these little tricks but I guess it really depends on each individual. What works for me might not work for another, especially considering the age factor (i'm 33), so there you go:
In general
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- it's not just about the jetlag, it's about learning how to sleep
- train your body to sleep little naps / rest during daylight
- get rid of the guilt if you wake up at 2pm... obviously your body needs it and this is normal if you work shifts.
- make sure your bedroom/house is quiet when you're back from a trip (let your flatmates/partner know you're trying to sleep)
- drink plenty of fluids (always)
Before the trip
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- 2 days before the trip, start going to bed later/earlier than usual depending on the time zone you'll be visiting so that you sort of shift your 8 hours sleep a little
- pack a bottle of mineral water in your crew bag: there is nothing worse than being thirsty and stuck in a hotel room with no water at 3am.
On the plane and abroad
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- if your company doesn't provide a crew rest area during the flight, management deserves to be sued... I could name many airlines but that's not the subject here.
- if you're only going for a bullet flight (less than 72 hours), do not change the time on your watch and eat/sleep when you feel hungry/tired. Don't feel guilty if you want to order roomservice at 3am (if available!)
- socializing and going out for a big night with the crew is nice but don't feel you have to. Your colleagues will miss you but at some stage, if exhaustion kicks in, it's stupid to deny the signals and end up sick. Your colleagues are no different and will understand.
- if you're overseas for more than 72 hours, I think it is however worth adapting to the new time zone (and enjoy dinners/partying out!)
- have a shower before you go to bed, it will relax your muscles and help you fall asleep.
- try to rest with your legs slightly higher than your body, it will help your circulation (and get rid of your platic shoes! Get a proper pair of cabin shoes!)
- eat healthy / cooked food rather than curries, burgers or raw food, especially in 3rd world countries/developping countries. Stomach ache is not gona help you sleep and, worse, you might end up with food poisonning.
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This is pretty much all I do.
Many airlines have a chapter in their cabin crew manual, dedicated to health and safety. You should find useful stuff there.
Now I'm not sure what circadian rhythms are... but if you explain, I'm sure someone will be delighted to give you further information.
Hope it helps,
FJ