If you fall asleep quickly you should be asleep within 30 minutes of putting your head on the pillow. If your sleep isn't interrupted It's important that you either don't wake up at all during the night, or if you do, you fall back asleep within 20 minutes. If you wake up feeling refreshed If you wake up feeling energetic and rejuvenated, not "beaten up," you're on the right track. If you can stay alert during the day If you can focus in the afternoons without needing excessive coffee or feeling sleepy, it means you've had enough sleep.