On average, it takes one day for each hour of time difference to recover from jet lag. If you’re going from New York to Istanbul for example (8 hour time difference) it will take you 8 hours to get back on schedule.
The transition can be made easier with some help from the easily accessible supplement melatonin.
Norman E. Rosenthal, MD, melatonin expert and professor of psychiatry, Georgetown University Medical School recommends 3 mg of melatonin (available at drugstores) 30 minutes before bedtime. For extended vacations, a sunrise alarm clock might do the trick and get you out of bed on time.