We’ve heard it since we were itty bitty babies: sleep is so important. But just what does sleep do, exactly, for your brain?

At bedtime, you shut down your computer, smartphone, and busy schedule, but for your brain, the workday’s just getting started. In fact, your brain remains highly active throughout your sleep so it can perform a host of functions that keep you humming through the day. It processes, restores and strengths during those critical hours when you are getting some shuteye.

When we sleep well, we wake up feeling refreshed and alert for our daily activities. Sleep affects how we look, feel and perform on a daily basis, and can have a major impact on our overall quality of life.

One of the vital roles of sleep is to help us solidify and consolidate memories. As we go about our day, our brains take in an incredible amount of information. Rather than being directly logged and recorded, however, these facts and experiences first need to be processed and stored; and many of these steps happen while we sleep. Overnight, bits and pieces of information are transferred from more tentative, short-term memory to stronger, long-term memory, a process called “consolidation.” Researchers have also shown that after people sleep, they tend to retain information and perform better on memory tasks. Our bodies all require long periods of sleep in order to restore and rejuvenate, to grow muscle, repair tissue, and synthesize hormones.

How much sleep do we need, really?

To get the most out of our sleep, both quantity and quality are important. Infants require 16 – 18 hours. Teens need at least 8 hours—and on average 9¼ hours—a night of uninterrupted sleep to leave their bodies and minds rejuvenated for the next day. And it’s advised that adults get 7 – 9 hours ever night.

If sleep is cut short, the body doesn’t have time to complete all of the phases needed for muscle repair, memory consolidation and release of hormones regulating growth and appetite. Then we wake up less prepared to concentrate, make decisions, or engage fully in school and social activities.

What role does each state and stage of sleep play?

NREM (75% of night): As we begin to fall asleep, we enter NREM sleep, which is composed of stages 1-4

N1 (formerly “stage 1”)

  • Between being awake and falling asleep
  • Light sleep

N2 (formerly “stage 2”)

  • Onset of sleep
  • Becoming disengaged from surroundings
  • Breathing and heart rate are regular
  • Body temperature drops (so sleeping in a cool room is helpful)

N3 (formerly “stages 3 and 4”)

  • Deepest and most restorative sleep
  • Blood pressure drops
  • Breathing becomes slower
  • Muscles are relaxed
  • Blood supply to muscles increases
  • Tissue growth and repair occurs
  • Energy is restored
  • Hormones are released, such as: Growth hormone, essential for growth and development, including muscle development

REM (25% of night): First occurs about 90 minutes after falling asleep and recurs about every 90 minutes, getting longer later in the night

  • Provides energy to brain and body
  • Supports daytime performance

Unfortunately, a person can’t just accumulate sleep deprivation and then log many hours of sleep to make up for it (although paying back “sleep debt” is always a good idea if you’re sleep deprived). The best sleep habits are consistent, healthy routines that allow all of us, regardless of our age, to meet our sleep needs every night.

Are you getting enough sleep each night to fully maximize your brain functionality? Now that you know what sleep does for your brain, be sure you and your family are setting yourselves up for a good next day, every day.