Jet lag

Jet lag is very common when travelling across time zones.
Jet lag is the feeling of profound sleepiness, fuzzy head and sometimes fading in and out with your surroundings.
It is caused by the abrupt reversal of your melatonin/cortisol levels as you leap across time zone.
During the day time your body produces a hormone called cortisol, which peak mid to late morning. This is when your energy levels should peak. Then as the cortisol levels taper off over the after noon, you prepare for bed, around 8-9pm. At this point the opposite hormone melatonin is produced in higher doses . This brings on sleep. Over night cortisol production is decreased. This 24 hour cycle is referred to as your circadian rhythm.
If you travel across a time zone your hormone levels become confused. Your body suddenly receives light (day time) when it has been producing melatonin (which is the night hormone). And vice versa with cortisol - hence why you often feel awake and have problems sleeping at night when you travel across time zones.
Your body can take up to 2 weeks to correct itself.
Read tomorrow about how you can manage jet lag