Sunny Im-Wang, Psy.D.
Getting restful, adequate sleep is crucial to good health—both physical and mental. We spend approximately one-third of our life sleeping, yet experts still don’t know exactly what happens when we sleep. But we do know that we can’t function well without it.
If you have children, you know that they need much more sleep than adults do. In fact, on average, a newborn baby needs between 12 to 18 hours of sleep per day. Toddlers require between 12 and 14 hours of sleep, and older children require an average of 10 to 11 hours per night[1]. Most adults need only 7.5 to 9 hours of sleep for optimal health and functioning.
Sleep Stages
As you sleep, you go through five different stages. These stages are dictated by your brain. Understanding the stages of sleep will help you better understand the effects on your child if he or she is awakened during a particular stage.
- Stage 1 – Thisis a transitional stage between being fully awake and asleep. The heart rate and body temperature begin to decrease, and the muscles start to relax. During Stage 1 sleep, which lasts only a few minutes, the brain is producing very slow waves known as theta waves[1]. If something were to awaken your child, he would probably say he had never gone to sleep.
- Stage 2 – This stage of sleep is very light and lasts for about 20 minutes. Your child can still be easily awakened, so if a dog barks or someone honks a car horn, he’ll likely wake up. Heart rate and body temperature continue to slow down slightly. Quick bursts of rhythmic waves, called sleep spindles[1] , are being produced by the brain during this stage.
- Stage 3 – Stage 3 is another transitional stage, taking the body from a light sleep to a very deep sleep. This stage is also known as the slow-wave sleep because the brain begins to produce slow, deep waves known as delta waves[1]. During this phase of sleep, blood pressure begins to drop. It will be much more difficult to wake your child during this stage. Some children (as well as adults) talk or walk in their sleep during this stage.
- Stage 4 – Like Stage 3, this stage is also regarded as slow-wave sleep, as the brain continues to produce delta waves[1]. It is the deepest stage of sleep and lasts for about a half hour. You’ll find that it is very difficult to awaken your child during this stage. If you do, expect him to be quite groggy for the first few minutes. Sleepwalking and talking often occur as people transition from this stage to a lighter sleep stage. If your child is prone to wet the bed, it will typically happen toward the end of this stage.
- Stage 5 – This unique, active stage of sleep is known as REM sleep because it is when rapid eye movement occurs[1]. Breathing is often irregular, and the heart rate is faster. This is the stage of sleep when dreaming takes place. Your child is most likely to remember a dream if he is awakened during this stage. The brain is very active during REM sleep, but the muscles in the arms and legs are essentially paralyzed.
The Sleep Cycle
Everyone repeats stages 2 through 5 several times throughout the night. Each cycle lasts about 90 minutes, so on any given night, your child will repeat this cycle several times until he wakes up[2]. Although the length of the cycles is the same, the majority of deep sleep takes place during the first part of the night, whereas the REM stages are longer during the latter part of the night.
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© 2011 Sunny Im-Wang, Psy.D. All rights reserved.
Reference:
- Epstein & Mardon, 2006. The ABCs of Zs: What Happens During Sleep? The Harvard Medical School Guide to a Good Night’s Sleep. Ch 2.
- Nicholi, 1988. The New Harvard Guide to Psychiatry
Dr. Sunny Im-Wang 