Anyone with teenagers will know that they prefer to go to bed later and get up later than most adults. This pattern occurs as a result of biological changes to the timing of their circadian body clock, which shifts later relative to the day/night cycle. These changes can make it difficult for teenagers to fall asleep at a time that allows them to get enough sleep before they need to wake. On school days, when they are required to wake early, sleep may be cut substantially short.
These biological changes are exacerbated by a number of factors, such as increasing independence in social interaction, setting of bedtimes, and use of electronic devices. The presence of electronic devices in the bedroom is associated with later bedtimes, shorter sleep and increased daytime sleepiness. Additionally, exposure to bright light from the screens of electronic devices at night can impact on the timing of our circadian body clock, resulting in later bedtimes.
While we know that the presence of electronic devices is associated with poor sleep, little is known about how the frequency and intensity of device use impacts sleep. Two studies have been published this month that investigate the effects of media use on teenage sleep. A group of Australian researchers have published findings from the ABC Big Sleep Survey of Australian sleep habits, which included questions on sleep duration, quality and timing; sleepiness; and the presence of electronic devices in the bedroom and the frequency of their use in bed.
Electronic devices were common in the bedroom with 70% of teenagers reporting have two or more devices in their bedroom at night and 80% having a mobile phone in their bedroom at night. The greater the frequency of use of computers in bed, the higher the likelihood of having short sleep, taking longer to fall asleep, and waking later on both weekdays and weekends. Teenagers who used computers every night were 2.4 times more likely to have short sleep on weekdays than teenagers who didn’t use computers. Similarly, using a mobile phone in bed increased the likelihood of taking longer to fall asleep and waking later on weekdays and weekends. Teenagers who used mobile phones in bed every night were 1.7 times more likely to have short sleep and 2.3 times more likely to have later bedtimes on weekdays than teenagers who didn’t use mobile phones.
Further to the Australian study, a study of Belgian teenagers has examined the how the frequency and intensity of electronic devices use in the hour before bed impacts on sleep. A substantial proportion (45%) of teenagers reported getting insufficient sleep and 63% had difficulty waking in the morning. They found that 45% used computers, 48% used their mobile phone and 13% played video games in the hour before bed. The more times per week teenagers used their phone or computer, listened to music or played video games before bed, the later their bedtimes on both weekdays and weekends. Additionally, the more time per night spent using mobile phones, computers (and the internet), listening to music or playing video games in the hour before bed, the later the bedtimes on both weekdays and weekends.
Similar to the Australian study, a large proportion of teenagers had electronic devices in their bedrooms at night. 86% of teenagers had a mobile phone in their bedroom at night, 53% had a computer, 70% had an mp3 player and 30% had a video game console. Not surprisingly, the absence of electronic devices was associated with earlier bedtimes on weekdays and weekends. The researchers also examined the impact of parental control of electronic device use and bedtimes on teenage sleep. The absence of rules for electronic device use was associated with more frequent and more intense computer use, television watching and music listening. Interestingly, no significant relationship between parental control and mobile phone use was found and the absence of rules around video game playing was associated with less intense and less frequent use. When there were parental rules for bedtimes, teenagers went to bed significantly earlier on both weekdays and weekends, than teenagers who did not have rules for bedtimes.
These findings highlight that it is the use of electronic devices both in the evening and in bed, rather than just their presence in the bedroom, that influences sleep quality, duration and timing. It also suggests that there may be some benefit from moderating (parental) influences but potentially the drivers for teenagers to use some devices (mobile phones) outweigh any parental influence. The influence of electronic devices may be highest for those with light-emitting screens and frequent use (a few nights a week or more) increases the likelihood of poor sleep patterns and insufficient sleep. It will be interesting to see these findings translate into strategies for improving teenage sleep. Although perhaps intuitive, these findings do support what we have been telling people: dim the screens on devices in the evening and avoid using electronic devices in the 2 hours before bed.