I probably don’t have to state this, but sleep is super important! Both the amount and quality of sleep are associated with cognitive functioning, memory, attention, and academic performance. Sleep is also related to physical health outcomes such as obesity, diabetes, and mental health including depression and substance use. For teens, who need sleep badly, there is data spanning 25 years that shows the average amount of sleep is decreasing. In the past five years in particular, there seems to have been an increase in the number of teens who sleep less than seven hours per night. This has been linked to a corresponding increase in screen use in this group.
How Much Sleep Should Someone Get?
It depends on age. There are recommendations from organizations such as the National Sleep Foundation, which suggests that:
Interestingly, in contrast to these recommendations, there is evidence that when given the chance to sleep ten hours, all ages of kids and at different levels of development sleep the same amount. Thus some researchers have proposed that kids of different ages sleep different amounts of time because of factors in the environment such as screen use.
Data suggests that half of teens get less than eight hours of sleep per night. Part of this can be attributed to the change in teen circadian rhythms which means they would preferably go to bed later and wake up later. Unfortunately, because school starts quite early, if they go to bed later they are left with not enough sleep. And in fact the data shows this. Around 40% of teens do not get enough sleep at night. The question is, do screens have a role? And if so, how much?
First, we know that almost 100% of adolescents have some sort of electronic device in their room. Older adolescents tend to have more, with up to four devices in their room! This is a problem for all sorts of reasons. For example, various research shows that having a TV in an adolescents’ bedroom is associated with going to bed later, reduced sleep time, and generally greater levels of sleep disturbance. Having a video game system or computer in the room has been shown to have exactly the same effect. There is evidence that having a phone in the bedroom is even worse.
How Can Screens Affect Sleep?
Well, there are theories… Having an electronic device in the bedroom is associated with both more daytime screen use and more nighttime screen use. This has three possible effects:
- Teens are using screens when they should be sleeping
- Screen use causes increased arousal, which interferes with sleep
- The light exposure from screens delays the body’s circadian rhythm
Each of these factors prevent sleep, causing problems in the daytime. What sort of problems? Well, around half of teens who use media a lot self-report getting poor grades. One in ten adolescents report driving while drowsy at least once per week. One study of over 1,000 teens even showed that basically all uses of technology predicted poorer health in teens.
What Is The Data On TV?
More recent research shows that television use, especially more than two hours per day, can result in sleep problems over time. And more than 50% of kids watch more TV than this each day. In general, there seems to be a dose-response of TV correlating with worse sleep, with more TV resulting in less sleep duration. In younger children, TV time is associated with increased resistance to going to bed also.
Not only is TV a potential problem, but the time when TV is watched is a problem. In particular, TV after 9pm is associated with reduced number of sleep hours and more difficulty waking up in the morning: Something no parent wants to deal with! The challenge here is that many teens report that TV is part of their wind-down routine and helps them sleep. The general research trends suggests otherwise of course. However, there are very few experimental studies where they manipulate when kids watch TV and monitor the effects on sleep, so much of this research is purely correlational.
What Is The Data On Video Games?
The story is similar to TV. In a nutshell, more time playing video games is associated with delayed sleep onset, reduced overall sleep, and more tiredness during the day. However, some experimental studies, where some kids are assigned to play games before bed while others get nothing, show that around two hours of video game playing within 30-180 minutes before bed can affect the sleep cycle. In particular, violent video games seem more disruptive when compared to non-violent games. Although this is interesting, it has not been studied with enough people to know anything conclusive. For now, the recommendation from the research is less than two hours of video games per day, and not within 30 minutes of bedtime.
The research says that both TV and video games can be detrimental to sleep, especially when used for more than 2-3 hours. There are not many experimental studies and the literature is mainly correlational. However, more TV and video games are associated with greater resistance to going to bed, reduced sleep, and tiredness. Using these devices within 30-60 minutes before bedtime appears particularly detrimental.
Tomorrow, I will post my article on how smartphones affect sleep.
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