Not long at all. I usually fall asleep as soon as I turn out the light. I like to read a bit too before I go to sleep - helps to slow down the brain! My only problem with falling asleep is if hubby gets to bed before me and gets a snore happening - then it's hopeless!
My husband on the other hand, goes to bed, usually after midnight, & reads & looks at You Tube, for many hours, until the laptop has nearly run down! He also has to sleep another room, because of his snoring. That used to wake me up about 5 times through the night!