The National Sleep Foundation’s 2014 Sleep in the Modern Family poll found that three in four teenagers, and 96% of teenagers between the ages of 15 and 17, bring some kind of technology into the bedroom. In total, the average adolescent gets up to nine hours of screen time per day.
The growing use of electronic devices for school, entertainment, and social media has many benefits. However, experts are becoming increasingly concerned about the effects of blue light from these electronic devices on the sleep-wake cycle. An estimated two in three teenagers regularly sleep less than the recommended amount, and screen time may be responsible for sleep deprivation and other problems.
The human sleep-wake cycle follows a circadian rhythm that mostly takes its cues from sunlight. When it’s bright outside, we become more alert. When it becomes dark, the body produces a hormone called melatonin that induces sleepiness.
Smartphones, tablets, computers, television screens, and some e-readers give off short-wavelength blue light that is very similar to sunlight. Not only does this light make us more alert, it also deceives the body into thinking it’s still daytime.
In response, the body produces less melatonin, interfering with the body’s natural sleep-wake cycle. The longer you spend on your screen, the greater the consequences for your sleep.
Screen time is linked to a host of insomnia symptoms in teenagers. By delaying the release of melatonin, screen time pushes back bedtime and leads to less restful sleep. As the majority of teens have strict school start times, a later bedtime usually results in less sleep overall and increased next-day sleepiness. Over time, consistently late weekday bedtimes and catch-up sleep on the weekend disrupt the circadian rhythm.
Scientists believe that children and adolescents may be extra-sensitive to the effects of blue light because their eyes let more light in. For this reason, limiting evening screen time in children and adolescents is especially important to prevent sleep problems.
In addition to suppressing melatonin levels, screen time for teens may directly eat into sleep time. Engaging in exciting or violent content before bedtime, or using social media, can boost alertness and impede sleepiness. Alertness and melatonin levels can also be affected by passive technology, such as a television running in the background or a smartphone that emits sounds, vibrations, and light.
There is some debate about if screen time actually causes insomnia in teens, or if teens who have trouble sleeping are simply more likely to use screens at night. To make matters more complicated, excessive mobile phone use has been linked to symptoms of depression and anxiety, which are themselves a risk factor for insomnia. It may be that sleep, screen time, and negative emotions interact to exacerbate unhealthy behaviors.
That said, the prevailing opinion is that screen time has a greater effect on insomnia than vice-versa. Studies show that 57% of teens who use technology in the bedroom suffer from sleep problems, and teens consistently report worse sleep when they have a television or small screen, such as a smartphone, in the bedroom.
Researchers aren’t sure whether or not certain devices are worse than others when it comes to sleep problems. Computers, tablets, smartphones, televisions, and game consoles have all been shown to impact sleep, especially when used in the hour before bedtime.
Some experts believe that sleep suffers more with devices that require interactive use, such as a smartphone or a video game console. Others suggest that smartphones might impact melatonin levels more than television screens since they tend to be held nearer to the face. Along the same lines, sleep appears to suffer more when teenagers use screens in a dark room, possibly because their pupils are more dilated and let more blue light pass through.
The more time a teenager spends on a screen each day, the more likely they are to have disturbed sleep. Also, using a phone to communicate with others near bedtime could lead to less sleep as teens stay up later to wait for a reply. Finally, keeping a phone on, unsilenced overnight is also shown to disturb sleep when alerts for incoming messages awake teens.
Sleep deprivation during adolescence can cause problems with mood, emotion, and academic performance. Teens who don’t sleep well are more likely to have problems with their peers, and chronic sleep loss can lead to a weakened immune system, depression, and suicidal thoughts.
Sleep loss and screens are both risk factors for obesity as well, especially when screen time takes the place of exercise. Sleep loss also leads to increased tiredness during the day, which can be very dangerous for young drivers.
Because teenagers need to use screens for academic and social obligations, organizations such as the American Academy of Pediatrics prefer not to put an exact number on the recommended screen time for teens. Instead, they urge parents to develop a personalized family media plan.
A family social media plan should include clear limits on screen time, and allot time for other activities such as sleep, family time, schoolwork, and exercise. Teens do best when they are given the chance to participate in creating their own guidelines, so consider sitting down and making a “screen time plan” together. As part of the ongoing mission to improve your teenager’s screen use habits and sleeping environment, you should:
Ideally, the bedroom should be a screen-free zone. Reserving the bedroom for sleep helps the brain wind down. However, it’s not always feasible to keep technology out of the bedroom. If your teen must use technology in the bedroom, ask them to turn their devices off about an hour before bedtime. Glasses or applications designed to filter out blue light also appear to minimize disruptions to teenagers’ sleep.
To help teenagers adopt healthy screen habits, parents should strive to be positive role models by limiting their own screen use.