A jet lag rule of thumb says it normally takes one day per time zone to get back to “normal” (flying west to east). That means, after a nine-hour time change on a flight from the US west coast to Germany, you'll need nine days before your body fully adjusts to Central European Time.
Jet Lag FAQ: How long will it take me to adjust? It allegedly takes one day per hour of time difference for the body to get fully adjusted. So for a 6 hour time difference, it would take 6 days for the body to completely adjust.
Most people find that jet lag is worse when traveling east than it is when traveling west. View Source . Jet lag differs based on the direction of travel because it's generally easier to delay your internal clock than advance it. Jet lag does not occur on north-south flights that do not cross multiple time zones.
It is widely acknowledged that jet lag is worse when travelling east, but this has nothing to do with the direction of Earth's rotation. Like many creatures, humans have a circadian rhythm that follows a 24-hour period and is kept in sync by the eyes' response to natural light levels over the day.
Common ways pilots avoid jetlag is staying hydrated, good rest, avoiding caffeine and alcohol, exercising, or sleeping on the airplane. For long-haul flights airlines use multiple pilots for the flight to allow each pilot to get some rest. The more time zones that are crossed, the worse the jet lag.
How long jet lag lasts will depend on several factors. These include how far you traveled, your body's unique rhythms and your overall health. Many people who experience jet lag feel better a few days after arriving to their destination. For some people, it can take up to one week to feel fully back to themselves.
Remember that anything over 6 hours flying time is considered long haul, but flights of longer than 10 hours are not uncommon either. One important thing to remember is to keep your seat belt fastened at all times in case of unexpected turbulence.