You want to know the scientific reason why you should never hit the snooze button? Let me hit you with some neuroscience here. Two words, sleep inertia. When you hit the snooze button, you're awake. As the alarm turns off, your brain then drifts back into sleep. Here's the thing that researchers have figured out. When you drift back to sleep after you've woken up, your brain starts a sleep cycle. Sleep cycles take 75 to 90 minutes to complete. When that alarm goes off again in nine minutes, and you're like, Oh, my God. Have you ever noticed you're in deep sleep when you drift back to sleep? That's because you're nine minutes in to a 75 cycle, and it takes your brain about four hours to get through that groggy feeling. When the alarm rings, get out of bed.