Sleep Cycles in Teenagers

Imagine showing up to class without your backpack; you’ll feel unprepared and off balance. That is what your brain feels like when you do not get enough sleep. Most teens know they need a full night's sleep, but between late-night studying and scrolling on social media, sleep often comes last. Even though it is easy to skip, sleep affects much more than just how awake you feel. It shapes your mood, focus, physical health, and how you deal with stress. Understanding how sleep works can help you plan your time and make sure you get the rest you need.

Sleep is not just turning your brain off for the night. Your body goes through a cycle with four stages. N1 is the lightest stage, when you are just starting to fall asleep. It lasts about 7 to 10 minutes, and you can wake up easily. In N2, your body relaxes more, your heart rate slows, and your temperature drops. This stage usually lasts 10 to 25 minutes. N3, or deep sleep, is when your body repairs itself, restores energy, and strengthens your immune system. Finally, REM sleep (Rapid Eye Movement) is when most dreaming happens, your brain is active, and your body stays still. Each cycle takes around 70 to 120 minutes, and your body goes through several of them every night (Suni, 2025).

Two systems in your body help control when you feel sleepy or awake: sleep-wake homeostasis and the circadian alerting system. Sleep-wake homeostasis works like a pressure gauge. The longer you are awake, the more your body wants to rest. The circadian alerting system is your internal clock. Sunlight during the day keeps you alert, and darkness at night tells your body it is time to wind down (Suni, 2025).

Daily habits can interfere with these systems. Stress, hunger, caffeine, and using devices late at night all affect your natural rhythm. Caffeine blocks a chemical called adenosine, which makes you feel sleepy. Blue light from phones, laptops, and TVs also lowers melatonin, the hormone that signals your body to rest (Central Ohio Sleep & Joint 2022). With less melatonin, falling asleep can be difficult, even if you feel exhausted.

Not getting enough sleep does more than make you feel tired. Over time, not getting the adequate amount of rest can raise the risk of heart problems, weight gain, a weaker immune system, and mental health issues like anxiety or depression (Suni, 2023). Studies show that 60 to 70 percent of American teens are not getting the recommended 8 to 10 hours of sleep each night (Garey, 2024). That means most teens start their mornings already low on energy.

It is possible to get better sleep. Following a regular schedule, even on weekends, helps your body know when to rest. Doing something relaxing before bed, such as reading, avoiding caffeine in the afternoon or evening, and putting away devices at least 30 minutes before sleeping, can help. These habits allow your body to stay on its natural schedule and make it easier to wake up prepared for the day (CDC, 2024).

Getting enough sleep is more than just resting. This is the time when your body recovers, your brain processes the day’s memories, and you regain energy for the day ahead. By prioritizing sleep and aiming for 8 to 10 hours each night, teens may find it easier to focus, feel more balanced, and manage daily challenges. Making sleep a habit is not always easy, but it can have a significant impact on how you feel and think.

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Works Cited:

Suni, E. (2025, July 25). Stages of sleep: What happens in a normal sleep cycle? Sleep Foundation. https://www.sleepfoundation.org/stages-of-sleep

Suni, E. (2025a, July 8). How sleep works: Understanding the Science of sleep. Sleep Foundation. https://www.sleepfoundation.org/how-sleep-works

Drdan. (2022, March 15). How can caffeine, blue rays, and blue light affect your sleep and health? - Central Ohio Spine and Joint. Central Ohio Spine and Joint. https://cospineandjoint.com/how-can-caffeine-blue-rays-and-blue-light-affect-your-sleep-and-health/

Suni, E. (2023, October 4). Teens and sleep. Sleep Foundation. https://www.sleepfoundation.org/teens-and-sleep

Garey, J. (2024, March 8). Teens and Sleep: The cost of sleep deprivation. Child Mind Institute. https://childmind.org/article/happens-teenagers-dont-get-enough-sleep/

About sleep. (2024, May 15). Sleep. https://www.cdc.gov/sleep/about/index.html