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Sleep Matters: sub-module 1 of 3 of sleep

You know that you should be sleeping every night, but do you know why? This module will teach you about why sleep is so important.


  • Give yourself enough time to sleep (7-9 hours). You need 7-9 hours of sleep each night, so make time for it, just like you make time for eating, exercising, and socializing.
  • Track your sleep to see if you’re getting enough. Keep a sleep diary, or use an app like Sleep Cycle - opens in a new window, to get a sense of how much sleep you’re actually getting.
  • Pay attention to your sleep quality, not just the hours you get.“Good sleep” isn’t just about logging a set number of hours -- it’s about the quality of your rest, too. Beware of telltale symptoms like fatigue, irritability, and attention problems.

Additional Resources

How Sleep Is Important

Benefits of Sleep

Watch this video to understand the benefits of sleep.

Sleep feels pretty awesome, but even better, it allows your body perform essential maintenance and offers many physical and psychological benefits:

  • A stronger immune system
  • Hormone regulation
  • Improved mood
  • Better concentration
  • Problem-solving ability
  • Better decision-making skills
  • Memory formation and consolidation
  • Increased productivity

Your Sleep Needs


Reality check: most adults need between 7 and 9 hours of sleep per night.

When you start skimping on sleep, it can have a negative impact on your physical and mental health. Prioritize sleep the same way you make time to go to the gym, spend time with friends, eat, and do all the other things that help you to feel your best.

To get a better sense of how many hours a night you’re sleeping, keep a sleep diary (link to PDF from Sleep Habits), or use an app like Sleep Cycle - opens in a new window (free on IOS and Android) to track your sleep.


Sleep quality is just as important as quantity. You might be suffering from poor sleep quality if you’re getting 7-9 hours of sleep per night, but still find yourself:

  • Unable to fall asleep within 30 minutes of going to bed
  • Forcing yourself out of bed in the morning
  • Struggling to stay awake during the day
  • Having trouble remembering things or staying focused
  • Feeling irritable or depressed

If this sounds like you, check out the rest of this module for tips on how to improve your sleep habits!

Have you ever been unable to stop yourself from falling asleep? One second, you’re trying to focus on your professor; moments later, you’re jolted back to consciousness. This is called microsleep, and it’s a major symptom of sleep deprivation. Microsleep is annoying when it happens in class, but it can be incredibly dangerous when it happens elsewhere (for example, while driving). So take microsleep as a warning, and work on improving your sleep.

Sleep Cycles

Good, restful sleep is made up of four stages, which occur in cycles of roughly 90 to 110 minutes.

Stage 1

You are somewhere between sleep and wakefulness. It’s during this stage that you might experience a “hypnic jerk”: that feeling of falling that jolts you awake.

Stage 2

You become less conscious of your surroundings as you enter light sleep. Your body temperature decreases and your heart rate slows.

Stage 3

Your breathing becomes very slow, your blood pressure drops, and your muscles relax as you enter deep sleep. You become difficult to wake up, and are likely to sleep through any disturbances. During this stage, your body grows bone and muscle, releases hormones, and works on your immune system.

REM Sleep

Your heart rate and breathing speed up, your limb muscles become temporarily paralyzed, and your eyes move back and forth. Your brain becomes extremely active, and you may experience vivid dreams. The REM stage becomes longer as the night goes on, with the first stage lasting only about ten minutes, and the final one lasting up to an hour.

Humans tend to spend about 75% of their sleep time in the first three stages of sleep, and 25% in REM sleep. Frequent nightly wakeups are not only frustrating, but keep you from progressing normally through a sleep cycle. This means you don’t get the full benefits of sleep, even if you’ve been lying in bed for 8 hours.

If you have trouble staying asleep at night, check out the section on Sleep Habits for tips on how to improve the quality of your sleep.