“ZZZ” – The Science of Sleep for Kids

by Robin Koontz

xSleep is something we all have in common, and perhaps also something that we know the least about. We have a vague idea about what sleep is: it’s what we do when we’re not awake. In a way, sleep is one of life’s biggest mysteries, even though we spend about a third of our lives doing it!

Students who are sleep-deprived are very likely to have problems in school. A child might fall asleep in class or have attention and/or concentration issues. He or she might be cranky and difficult to manage because of troubled sleep. Sleep disorders can also cause a variety of health problems. It’s a topic worth discussing for those reasons, but also a good opportunity to learn about the science and mystery of sleep.

What is sleep?

Sleep is the ultimate power booster. When we sleep, everything inside of us rejuvenates for the next daily challenge. During sleep, the brain maintains proper blood sugar levels, regulates hormones that control appetite and metabolism, reduces the risk of high blood pressure, and even boosts the immune system. A good night’s sleep also uplifts our mental well-being. Sleep helps us feel happier and less frustrated or anxious. We can focus and think more clearly and also more creatively. Memory is improved. A well-rested person is more alert and able to make good decisions.

It’s only been in the last 50 years or so that scientists have had the means to understand a lot more about sleep than they knew in the past. They still don’t completely understand everything about sleep. They do know that people, and all other living creatures, need to sleep in order to survive.

What happens when we sleep?

Sleep scientists have pinpointed all the typical sleep patterns, and the factors that can interrupt those patterns. During sleep, the brain is still hard at work. While we snooze, it processes information and forms memories while regulating breathing, heart rate, and other functions. There are four stages of normal sleep. The first is the beginning of non-rapid eye movement (NREM) sleep. N1 is a light sleep that usually lasts a few minutes. It’s easy to wake someone up during N1. During the N2 stage, the body relaxes. During stage N3, brain waves slow down and the body enters “deep sleep.” Some also call it “slow-wave sleep.” It’s not easy to wake someone up at this stage of sleep. FYI, there used to be four recognized categories of NREM (N1, N2, N3 and N4), but in 2007, N3 and N4 were combined into just one stage.

Finally the body enters the last stage, REM (rapid eye movement) or R sleep. Now the brain waves speed up! Eyes stay closed, but flicker back and forth in rapid movements. This is when the most vivid dreams, and sometimes nightmares, usually occur. Why don’t we thrash about during this period of sleep when we might dream about being chased? Because the brain paralyzes muscles during R sleep. The paralysis is called atonia.

After a period of R sleep, the cycle will start up again with N1. With each cycle, the time spent in R sleep increases. In adults, the entire cycle will last about 1-1/2 to 2 hours. An adult will cycle four to six times in about an 8-hour period. Children under age 10 experience shorter cycles.

More of the science behind sleep can be found in this Teacher’s Guide from NIH:


Not Always a Good Night

Meanwhile, not everyone sleeps through the four cycles. Insomnia is the inability to fall or stay asleep. It is the most common sleep disorder and has a variety of causes. Obstructive sleep apnea (OSA) happens when the soft tissue in the back of the throat relaxes too much, collapsing and blocking the upper airway. People with OSA will stop breathing, which usually wakes them up! Then there are people who are sleepy all the time. This condition is called narcolepsy. People with narcolepsy will get the irresistible urge to sleep in all kinds of situations. It can be misdiagnosed if the person is having other sleep issues such as insomnia, or has bad sleeping habits. Parasomnias are the odd behaviors exhibited while some people sleep. Sometimes they act out their dreams as they sleep. They might punch, kick, yell, grind their teeth, wet the bed, walk around, and even eat.

The list of sleeping disorders goes on and on. Plus, pain, diseases, medications, diet, and other lifestyle habits can affect normal sleep. Determining if someone has a sleeping disorder isn’t always easy. The American Academy of Sleep Medicine has sleep centers all over the country to help people with sleeping disorders. Perhaps you can invite someone to your school to talk to the kids about what they do.

Students can study sleep simply by starting a sleep journal about their own sleeping habits and how they feel during the day, too. They can compare notes with others. Why do some people seem to need more sleep than others? Are they tired during the day or do they have energy? Tracking dreams, the good ones and the bad ones, can give kids a chance to talk about them, especially the troubling ones. Did they have a stressful day? Did they eat spicy pizza? Comparing notes and sharing can give kids a sense of camaraderie with others. After all, sleeping and dreaming is something we all have in common. Plus, dream journals are great writing sparks. Mary Shelley wrote her most famous work, Frankenstein, after having a vivid dream!

This is a great article about nightmares to share and talk about, especially with younger kids:


In the Jungle the Lion Sleeps…

All living things have a sleep cycle of some kind. In mammals as well as many other animals, sleep is similar to what humans do. Water animals such as dolphins and whales that have to surface to breathe do have a unique way of sleeping. They sleep using half the brain at a time! That way they remain “half awake” enough to remember to breathe and to stay aware of their surroundings in case of danger. How do other animals sleep? Do plants also sleep?

Many mammals hibernate in winter. Hibernation is not really sleep. Animals such as the American black bear can go for 100 days without eating, drinking, or moving. In hibernation, the animal’s heart and breathing rate slow down. Their body temperature drops, too, especially in smaller animals that hibernate. A fun project could be to have students choose an animal that hibernates and present a study about it. For instance, turtles can breathe underwater while they hibernate. A good general list is here:


There are also some interesting discussions among scientists that address these questions:

What are the advantages of being able to hibernate?

What if people could hibernate? Why would they want to?

Send kids on a quest to learn why people could benefit from hibernation. I won’t give away the answers.

Finally, you can also discuss the ways they can get healthy sleep. Here’s a terrific poster:

Top 10 Healthy Sleep Habits for Children & Teens


I hope this information sparks your own ideas for sleep projects in the classroom. Sweet dreams!

Robin Koontz

Robin Koontz is an award-winning freelance author/illustrator/designer of a wide variety of nonfiction and fiction books, educational blogs, and magazine articles for children and young adults. Raised in Maryland and Alabama, Robin now lives with her husband in the Coast Range of western Oregon where she especially enjoys observing the wildlife on her property. You can learn more on her blog, robinkoontz.wordpress.com.