When should you go to bed to get 7 or 8 hours of sleep? This backwards calculator helps you determine when you should go to bed based on your wake-up time, the number of hours you want to sleep, and the number of minutes you need to unwind. Get notifications for when to go to bed and when to stop drinking caffeine (6 hours before bedtime based on the study cited below). If you feel a little tired and want a little more sleep, change the number of sleep hours. If it takes you more/less time