Calculate how many time zones you will be crossing. Generally, flying through one or two time zones will create little havoc with your body. If you are flying over more three or more time zones, however, your body will react negatively to the change.
Make note of the time it currently is in your home destination. You will need this to figure out how disrupted your body’s internal clock is.
Take a look at how many time zones you have left since your departure city. Add a day if you are flying east. If you have flown more than six time zones, then it will take you six days to recover. If you have flown west, it will only take three days to recover. This is because when you fly west, you are essentially gaining time, while flying east causes you to lose time.
