4. YOUR BRAIN IS BEING TUNED UP

Ever leave your vehicle overnight with the mechanic? Well, night-night time is your brain’s mechanic. Here’s all that happens when you sleep:

– Your brain clears toxic byproducts

– Your brain is converting short-term into long-term memories

– Your brain is “defragmenting,” or getting rid of the bits of info you don’t need

– Your brain is restoring the necessary bits of info that wasn’t ingrained during the daytime.

5. WE “DEEP SLEEP” ONLY 20% OF THE TIME

As we discuss in the next section, we sleep in four cycles. “Deep sleep,” or the period of sleep prior to REM sleep, occurs only 20% of the time spent sleeping. “It’s also called our deepest sleep,” adds Philip Gehrman, Ph.D., and assistant professor at the University of Pennsylvania,

“It’s also caused our slow-wave sleep because our brain waves are these slow, high-amplitude waves.”

6. YOU SLEEP IN 4 STAGES

Scientists divide sleep into four stages, with each full sleep cycle taking about 1.5 hours to complete. On average, we’ll go through roughly five rotations in 8 hours of shuteye. Here’s a snapshot of what each stage looks like:

Stage 1: Easily awakened, muscles may relax and twitch, eye movement slows.

Stage 2: Eye movements further slow, body temperature drops, lose sense of environment, brain waves slow, eye movement stops.

Stage 2-3: Blood pressure drops, muscles relax, tissue growth and repair, energy is restored, hormones are released, very slow brain waves.

REM: Brain is active and dreaming, eyes dart, muscles are paralyzed, irregular breathing and heart rate.