School start times and late screen time exacerbate sleep deprivation in US teenagers

Parents and caregivers face the old struggle of getting their groggy children out of bed every morning, as the school year begins across the U.S. It can be especially difficult for parents of teenagers and preteens.

This can sometimes be attributed to teenage laziness. A healthy person may not be able to wake up naturally without an alarm because they don’t get the sleep that their brain and bodies need.

This is because studies have shown that teens need more than nine hours of sleep each night to stay physically and mentally fit.

It is unlikely that your teenager gets enough sleep. According to the Centers for Disease Control and Prevention, less that 30% of high school students, or those in grades 9-12, get the recommended amount of sleep. Nearly 60% of middle school students in grades 6-8 don’t get enough sleep at night.

My laboratory’s research shows that teens get too much sleep.

I am a professor in biology. I have been studying circadian rhythms and sleep for more than 30+ years. My laboratory at the University of Washington has been researching sleep among teenagers in Seattle for seven years. As in other parts of the U.S., high school students in Seattle don’t get enough sleep. The objective measurement of sleep among 182 high school seniors and sophomores revealed that only two had slept more than nine hours each night during school.

Our research and others have shown that there are three main factors behind the lack-of-sleep epidemic. These are a lack of daylight in the morning, and excessive exposure to bright light and screens in late evening.



Teen sleep biology

Two main factors in the brain determine when people go to sleep, wake up and fall asleep. The first is the so-called “wakefulness monitor”, a physiological timer which increases our need for sleep the more we remain awake. This is partly due to the accumulation of chemical signals from neurons , such as adenosine.

When we’re awake, adenosine builds up in our brains. This leads to increased sleepiness. For example, if a person wakes at 7 a.m., the chemical signals build up and eventually lead to sleepiness. Usually, this happens in the late evening.

A 24-hour biological clock is the second factor that determines the sleep/wake cycle. It tells the brain when it should be awake and when it should go to bed. The hypothalamus is the location of this biological clock in the brain. It is made up of neurons that coordinate brain areas responsible for regulating sleep and wakefulness in a 24-hour cycle.

They operate in relative isolation from one another. They are however coordinated under normal conditions so that someone with an electric-powered light source would fall asleep late at night, between 10 and 11 p.m., then wake up early in the morning, usually around 6 to 7 a.m.

Teen health is dependent on adequate sleep, but there are many factors that prevent teens from getting enough.

Why is it that teenagers want to wake up earlier than their parents and go to bed later?

The biological clock and the wakefulness tracker conspire to delay sleep during adolescence. First, teens can wake up later than their wakefulness tracker allows them to feel sleepy enough.

The second is that the biological clock in teenagers is delayed. This happens because it reacts differently to light cues to reset the clock every day and sometimes it runs at a slower speed. This results in a sleep cycle that is a few hours slower than for an older adult. For example, if an older adult senses the signal to fall asleep at 10 or 11 p.m. it won’t happen in teenagers until midnight.

What school start times mean

Some school districts have implemented to help teens get more sleep. They are delaying the start of middle and high school classes. According to the American Academy of Pediatrics, schools should not be opened before 8:30 a.m.. However, the majority of high school in the U.S. start at 8 a.m..

According to sleep experts, the Seattle School District delayed the start of middle school and high schools by almost an hour starting with the 2016-2017 year. This was due to the delay in the school’s beginning times from 7:50 a.m. until 8:45 a.m. Our team found that students received 34 minutes of sleep each day in a study they conducted after the district adopted the plan. This is a significant improvement by sleep medicine standards. Additionally, attendance and punctuality of students improved and their median grades increased by 4.5%.

Many school districts continue to have school start times that encourage sleep deprivation among teenagers despite a wealth of research evidence and advice from nearly all national sleep experts. Daylight saving time , which is when clocks are one hour ahead of the springtime, further aggraves early school starts. This time shift , which could be permanent in the U.S. in 2023, exposes teenagers to artificially darkened mornings that can exacerbate their naturally delayed sleep times.

Promoting healthy sleeping habits for teens

Children should not only learn about school start times, but also how to have healthy sleep habits.

Bright daylight exposure, especially in the morning, helps push our biological clock forward. This will encourage a more natural morning sleep time and a earlier bedtime.

Contrary to this, the brain is highly stimulated by light at night (including screens). It blocks the production of natural signals like melatonin. This hormone is made by the brain’s Pineal gland when the night comes and in response to darkness. Artificial light at night can cause biological clocks to delay, leading to a later bedtime, and later wake up time. So the cycle of having a sleepy, yawning teenage boy get up for school starts again.

Many schools do not teach good sleep habits and proper sleep timing. Parents and teens are also often unaware of their importance. Chronic sleep deprivation can disrupt every physiological process and is consistently linked with disease, such as anxiety and depression, weight gain, and addictive behaviors.

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