Audience: Middle and High School Students
Fun Fact: Humans are the only mammals that can purposefully delay sleep. Photo by Gregory Pappas from Unsplash.
The sun tucks itself away, surrendering to the subtle glow of the moon. The sounds of drumming basketballs and children dissipate with the daylight, until everyone is snugly tucked beneath bed sheets. For kids, the bedtime medley of stories, hugs, and kisses settles lively minds to a drowsy state of slumber. The hours pass quickly when the body is asleep, until the familiar, dreadful ring of the alarm drags you back into the real world. Sleep is something completely routine, but also a strange concept. We close our eyes, surrender our body to our exhaustion, and emerge feeling recharged and refreshed. We have been raised under the notion that sleep is a necessity, as preached by most adult figures in our life. However, what happens when we sleep? Why is sleep such a crucial component in our lives?
First off, sleep is not as simple as shutting one’s eyes. Sleep is defined as the resting state with alterations in brain activity, heart rate, body temperature, and breathing. As an infant, between 14 and 17 hours are needed on average, but this number becomes smaller and smaller with time. School-aged children between the ages of 10 to 12 need nine to 12 hours of sleep per night, teenagers need eight to 10 hours, and those 18 or older need seven to nine.
There are two clear stages of sleep: REM sleep and NREM sleep. Both REM and NREM are extremely important, as essential to health and development as food and water. Contrary to popular belief, the mind remains incredibly active even as the body slips into a restful state, alternating between these two different cycles.
The first cycle is the NREM cycle. Once you fall asleep, you will usually enter Stage 1 NREM. This stage helps the brain reinforce memories and learned skills. Stage 1 NREM is the lightest form of rest and accounts for approximately 5% of normal sleep time. Afterwards, the body transitions to Stage 2 NREM. This is the stage where the brain organizes and categorizes memories. While this stage is still categorized as relatively light sleep, there are larger stops between electrical activity in the brain, and the brainwave frequency slows. This takes up around 45% of sleep time, which is consistently more than any other stage of sleep. Usually, one will cycle through a couple rounds of Stage 2 NREM sleep. Following this stage is Stage 3 NREM sleep, taking 25% of sleep time and being the deepest state of sleep one can experience in the NREM sleep category. If you’ve ever had difficulty shaking someone awake from slumber, it is likely because you woke them in the middle of Stage 3 NREM sleep. This is an especially important part of sleep since brain waves are generally stronger despite still being slow, helping repair bodily functions and boosting the immune system. Without this stage of sleep, the body would not feel strong and rested, regardless of the amount of time slept. Often, the body will optimize to attain the most amount of Stage 3 NREM sleep as possible. After Stage 3 NREM sleep, the body might cycle back to Stage 2 NREM sleep, eventually reaching REM sleep.
So what is REM sleep? REM sleep, the second category of sleep, is what follows the NREM cycle, accounting for around 25% of total sleep time. The first cycle of REM sleep lasts about ten minutes in length. Each night of sleep consists of multiple cycles of each stage of NREM sleep and REM sleep. Brain activity during REM sleep and brain activity while one is awake are largely indistinguishable. This is mainly due to the fact that REM sleep occurs when the mind is the most active and is also the time that people dream. During dreams, the eyes move back and forth in rapid movements, which gives the REM cycle its name. While the dreams that accompany REM sleep seem to be very prominent,
So why is sleep stressed as one of the most fundamental parts to our development? Sleep is important to the body for various reasons, but there are three main ones to note when viewing the benefits of slumber. The brain uses sleep for brain maintenance, tidying up memories and learned information so that they’re more easily accessible in the future. Furthermore, sleep is used for recovery. During illness or injury, sleep is a critical part of the healing process, as the body repairs itself faster when asleep. Lastly, sleep is used to store energy. While you are awake as an active human being, the cells inside the body must burn stored resources to supply energy throughout the day. During sleep, a significantly smaller amount of energy is used, giving the body rest and an opportunity to create and store more energy.
Clearly, sleep is far more complex than one would think. While many parts of the sleep cycle are still a mystery, what has been discovered truly shows how intricate and important the process of sleep is. Tonight, when you turn off your light and slip beneath your covers, realize that you aren’t simply resting and unwinding. You’re setting your body up for success, letting it recover and strengthen your mind.
Bibliography:
Cleveland Clinic. “Sleep.” Cleveland Clinic, my.clevelandclinic.org/health/body/12148-sleep-basics. Accessed 27 Dec. 2023.
NH. “Brain Basics: Understanding Sleep.” National Institute of Neurological Disorders and Stroke, U.S. Department of Health and Human Services, www.ninds.nih.gov/health-information/public-education/brain-basics/brain-basics-understanding-sleep. Accessed 27 Dec. 2023.
Suni, Eric. “Stages of Sleep: What Happens in a Sleep Cycle.” Sleep Foundation, 8 Dec. 2023, www.sleepfoundation.org/stages-of-sleep.
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