What Is Sleep?
Sleep is a period of rest. It consists of REM and Non-REM sleep, 2 distinct states that alternate in cycles and reflect differing levels of brain nerve cell activity.
Non-Rapid Eye Movement (Non-REM) Sleep
Non-REM (or NREM) sleep is also termed quiet sleep. Non-REM is divided into 3 stages of progression and with each descending stage, awakening becomes more difficult.
Rapid Eye Movement (REM) Sleep
During REM sleep the brain is highly active. This stage is called active sleep. Most vivid dreams occur in REM sleep. In REM sleep, brain activity is comparable to that in waking, but the muscles are virtually immobilized, which prevents people from acting out their dreams. Except for vital organs like lungs and heart, the only muscles not immobilized during REM are the eye muscles. REM sleep may be critical for learning and for day-to-day mood regulation. When people are sleep-deprived, their brains must work harder than when they are well rested.
The REM/Non-REM Cycle
The cycle between quiet (Non-REM) and active (REM) sleep generally follows this pattern:
- After about 90 minutes of Non-REM sleep, eyes move rapidly behind closed lids, giving rise to REM sleep.
- As sleep progresses the Non-REM/REM cycle repeats.
- With each cycle, Non-REM sleep becomes progressively lighter, and REM sleep becomes progressively longer, lasting from a few minutes early in sleep to perhaps an hour at the end of the sleep episode.
Why is Sleep Important?
Sleep isn’t just a time when your brain and body shut down. Your brain and body accomplish important tasks during sleep that help you stay healthy and function better when you’re awake.
Getting enough sleep helps you think more clearly and react more quickly. During sleep, your body produces hormones that help repair cells and tissues and fight off illness.
Not getting enough sleep can be dangerous, not only affecting your performance, but your health and mood, too. Studies show that lack of sleep may cause you to:
- Have a slower response time
- Take more risks or make unwise decisions
- Be irritable
- Behave poorly
- Have trouble with relationships
- Become depressed more easily
- Have high blood pressure, heart disease, diabetes and other medical conditions
- Become overweight
How Much Sleep Do I Need?
How much sleep you need depends on your age. Here are standard daily (or nightly) guidelines:
- Newborns: 16–18 hours
- Preschoolers: 11–12 hours
- School-aged children and teens: At least 10 hours
- Adults: 7–8 hours
You probably have heard of a biological clock which governs growth, reproductive cycles and aging. There are also bodily rhythms, known as circadian rhythms, which are controlled by a biological clock and work on a daily time scale.
You might have already noticed in yourself or in others that sleepiness doesn't just keep increasing as it gets later. Rather, the drive for sleep follows a cycle, and the body is ready for sleep and for wakefulness at different times of the day.
How to Get to Sleep
If you have a hard time getting to sleep, try these tips:
- Maintain a regular sleep schedule. Go to bed and wake up at the same time every day.
- Relax before bed. Make it part of your bedtime routine.
- Take a hot bath before bed.
- Maintain a cool temperature in your bedroom.
- Remove sleep distractions from your bedroom, such as TV, noises or bright lights.
- Exercise no later than 2–3 hours before going to bed.
- Avoid caffeine and nicotine.
- Avoid alcohol before bed. While alcohol can help you get to sleep, it doesn’t help you stay asleep.
- Don’t eat or drink too much before bed so your sleep isn’t disturbed by indigestion or the need to urinate.
- Limit naps to no more than 1 hour — and don’t nap after 3 pm.
- Get at least 30 minutes of natural sunlight each day. Daylight helps regulate sleep patterns.
- Don’t lie in bed awake. Get up and do some relaxing activity until you feel like sleeping.
Sleep Disorders
You may have a sleep disorder if it’s hard for you to fall asleep or stay asleep at night, or if you wake up feeling tired or feel exhausted during the day.
Common sleep disorders are:
If you continuously have trouble falling asleep, staying asleep, or have excessive sleepiness during the day, talk to your health care provider or request an appointment with one of our sleep specialists.