Sleep, Screens and Adolescents

Maria M. Hadjimarkou, PhD - Lecturer School of Psychology University of Sussex

Adolescence is a time characterised by growth acceleration and major changes in the appearance and behaviour of our youth. The brain also changes during this time, as it fine-tunes itself and prepares for adulthood. It is not a secret that this phase of development is sometimes accompanied by mood swings and the emergence of some mental health difficulties.

Sleep also changes during this time, not so much in terms of need, but in terms of timing. There is a decrease in the pressure to go to sleep at the usual time, so sleep is delayed. Gone are the days when they would be ready to go to bed at 8 pm and wake up early in the morning, energetic and ready to do things. This is not part of a rebellion tactic, it is part of the changing brain scheme, where the biological clock, a small area inside the brain, is changing its ‘ticking’ to a slower pace which leads to this general shift in sleep and wake time. This shift has been observed universally, across continents as well as in several animal species. In humans, it is estimated that the delay can vary between 1-3 hours, with girls displaying this delay about a year earlier than boys.

Although there is a delay in timing, the sleep need is still high compared to adults. The fact that adolescents are students and have to wake up early for school is compounding this phenomenon by cutting sleep short for these souls. A delay in going to bed would be nicely balanced if it was accompanied by a delay in waking up, which is what is observed during weekends or school holidays. During the school week though, this shift is lopsided with delayed bedtimes and early wake times (see graph). What is the result? Sleepy adolescents have trouble being truly alert and are not ready to learn in the morning. Several studies suggested that the first couple of hours in school are somehow ‘lost’ because these young people are still in sleep mode. This is more of an issue in the US where commuting takes longer, and school times start generally earlier than in the UK. Vocal scientists in this area have managed to create a political case for this and achieved a delay in school start times for secondary schools in some states, to allow adolescents to complete their delayed phase of sleep and join school later in the day when they would be more alert.

This natural shift in timing is compounded by the current trend in adolescents to use this extra time of wakefulness to chat and socialise with others using smartphones and computers, scroll social media and watch TikTok and YouTube videos. It may be beneficial to interact and stay connected with others rather than to feel lonely. However, there may be a fine line between staying connected and interacting in a positive way and staying connected out of fear of missing out and experiencing anxiety because of what others are doing or seeing things that may be disturbing. So, although there is a legitimate reason for a delay in bedtime and waketime for our teens, there is a point of concern when it comes to this natural shift being extended artificially to a much greater shift than it has to be.

Studies that track behaviour over several years have noted a gradual decrease in the time that adolescents sleep, with a big drop around 15 years of age that continues until about 19 years when it starts to bounce back. This major drop in sleep time or ‘the great sleep recession’ as it was called, is a replicated trend, meaning that other studies found this decrease in sleep among adolescents in recent years. This trend is accompanied by another trend, an upward trend in mental health difficulties, in feelings of hopelessness and sadness. Some also report a drop in the time spent with friends compared to previous years.

Do parents have a role to play in this? Parents enforce the bedtime for younger children but it seems that during adolescence, based on what surveys tell us, they let go of this role and allow adolescents the freedom to decide when they go to sleep. Parents seem to give up the role of bedtime enforcers, which they held during childhood, to assume the role of the alarm clock, despite the fact that 90% of them acknowledge the importance of sleep. Bedtime enforcement is one of the best predictors of good quality sleep. The other one is having electronics in the bedroom.

Another component of the modern family landscape is an increase in ‘alone-together’ time, meaning that we all sit together as a family but we do not interact with each other. Instead, we each have a device that we attend to, a computer, a tablet, etc. so everyone is busy together. Using electronics for leisure has contributed to a more sedentary lifestyle in both adolescents and adults which can have a negative impact on both our physical and mental health. So what would happen if we were to remove these electronic distractions? In an interesting study in Denmark, researchers took away smart devices from some families and allowed screen time of a maximum of three hours per week. What they found was about an hour more of physical activity and play each day compared to those with access to smart devices.

So, in thinking of a vulnerable time in human development, adolescence is challenged by a biological shift in the timing of sleep and wakefulness, compounded by early school times and exposure to screens like never before. For some, this may shed light on the upward trend of mental health difficulties whereas for others there may be a case for that only for those who may be more vulnerable, to begin with. It may be worth evaluating the current state of things. The government may pressure companies to protect our youth however few feel confident that this will lead to a significant change in the current state of things. Key Reference: Buxton OM, Chang AM, Spilsbury JC, Bos T, Emsellem H, Knutson KL. Sleep in the modern family: protective family routines for child and adolescent sleep. Sleep Health. 2015 May 1;1(1):15-27. doi: 10.1016/j.sleh.2014.12.002.