What medicine is good for sleeping on an 11-13 hour flight? I am going on a flight for 11 hours going and 13 hours coming back. I really want to sleep on the plane so I was thinking about taking some medicine to make me go to sleep. I here taking Benadryl just for sleeping is bad due to the side effects. Also my parents are kind of nervous giving me any type of sleeping medicine, so what are the side effects of the drugs. Also how long does it take for the medicine to go in effect.