"In general, our bodies do better when they can get used to a single clear rule — to get out of bed the moment the alarm sounds," Ariely says. "When we play with the snooze button, our bodies get a confused message — sometimes we hear the beeping and get up, sometimes we hear it and stay put for 10 more minutes, sometimes we lie there for another 20 minutes, and so on."
Your alarm clock, in many ways, should be training your body how to react. Like Pavlov's dog, your body should be conditioned to respond appropriately to the stimulus of the alarm clock. But the snooze button is a mixed message. It's not only screwing up how your body is trained to react, going back to sleep isn't doing you any good. You don't reach a state of restorative sleep and instead of starting the process of waking up, your body is beginning the process of falling back asleep, which is counterproductive for your day and can result in sleep inertia.