It is widely acknowledged that most adolescents do not get sufficient sleep, leading to lowered emotional regulation, compromised cognitive and academic functioning, and health problems. Many primary causes have been proposed by sleep researchers.
Poor sleep hygiene has been proposed, meaning behaviors such as irregular bedtimes, not adhering to a consistent calming bedtime routine, failing to ensure a dark, quiet, cool sleep environment, and consuming caffeinated beverages. For some adolescents, structural aspects of the home and neighborhood environment are not conductive to good sleep. Noise levels inside and outside the house are hard for adolescents to control as are ambient temperature and humidity. Stress deriving from family conflict, peer conflict, bullying, feeling left out, and discrimination have all been linked to poor sleep. Lack of parental monitoring and regulation of sleep habits have been proposed as problems. Many argue that early school start times do not provide enough time to get sufficient sleep.
All of these are no doubt involved in combination to some degree for most teens. But of all the causes of poor sleep, there is one that I have come to believe may be the biggest cause – use of smartphones, computers, tablets, gaming devices, and TV not only during the day, but in the evening.
The Pew Research Center estimates that around 95% of American teenagers have a smartphone, 90% have access to a desktop or laptop computer, and 80% or more have access to a gaming device. More than half report that they are on their phones “constantly” and estimates are that the average time of use is more than five hours daily. Around 40% report using phones eight or more hours daily. Many teens use social media in the evening before going to sleep and a substantial number do not silence their phones at night, leading to wake-ups after going to sleep.
Much has been made of the fact that after puberty, melatonin release is delayed such that most adolescents become “night owls” and cannot go to sleep until late evening. In fact, this is the primary basis for the nationwide movement to start schools later. While there is much evidence for this developmental sleep phase delay, it is also true that excessive evening screen use suppresses melatonin production.
One experimental study conducted in the homes of adolescents showed that even one hour of screen use suppressed melatonin by 23%. Two hours of use, the maximum screen time tested in the study, reduced it by 38%. The authors compared the results with previous studies they had done with adults (mean age 28 yrs) and found that the adolescents were more sensitive than adults to screen light (Figueiro & Overington, 2016). Beyond the fact that screen use consumes times during hours available for sleep, there is a biological basis for screen usage leading to compromised sleep.
The good news is that some research suggests that reducing screen time can lead to earlier sleep onset and longer sleep. Perrault and colleagues (2019) conducted a study of over 500 12- to 19-year-old adolescents who were given instruction about how screens are detrimental to sleep. Half of the adolescents were asked to reduce screen time after 9:00 PM for two weeks and were compared with a control group who did not receive the intervention. Sleep data were collected with actigraphy, and participants came to a lab to complete surveys, have melatonin levels measured, and perform a sustained attention task. Those in the experimental group had earlier sleep onset times and longer sleep duration times than those in the control group. They also performed significantly better on the attention task.
Granted, results like these are not accomplished easily. Many parents are not willing or able to enforce rules about evening screen time. Many adolescents are, no doubt, unwilling to even try reducing screen time. But the parents and adolescents who are willing and able to do so are likely to see important benefits. I hasten to add that manufacturers and providers of devices and social media platforms bear some responsibility for the unintended negative consequences of what they sell. They should be held accountable to create some technological solutions to the problems they have helped to create. Further, they should be funding education programs and intervention projects to mitigate harm.
