Electronics Before Bed: When Does It Affect Sleep?

With the explosion in recent years in the use of electronic media-including television, computers, video-gaming, the Internet, mobile telephones, and music-there is growing concern about their effect on sleep, especially the sleep of children and adolescents. A big concern for these youngsters, of course, is that sleep affects memory performance and concentration, much-needed skills in the classroom.

In 2010, we reviewed 36 studies conducted on minors that involved sleep issues and electronics use.¹ Our most consistent finding was that excessive media use results in a shorter sleep time and delayed sleep.

Since we published that study, newer versions of electronics have been released and their use has become more widespread. Here I comment about recent updates in the sleep and technology field.

What’s Changed
There has been a steady increase in correlational studies because many authors see technology use as an important variable to insert into their sleep surveys. I was involved in such a study that was conducted by the National Sleep Foundation. However, I am more interested in controlled laboratory studies.

We recently tested whether the light from iPads affects sleep. Although our findings are not yet published in a peer review setting, Flinders University released information on them showing that teens using iPads for a moderate amount of time (an hour) before bed are still likely to get a good night’s sleep. The small study evaluated 16 adolescents (age range, 14 to 19 years) over 3 weeks at the university’s sleep research laboratory. They watched a movie or played a game on the iPad, using the brightest screen setting. The light from their iPads had no effect on their sleep.

We also tested the notions that the blue light content from LED-backlit screens can affect sleep and that new interventions designed to prevent this problem actually work. We asked teenagers to use an iPad on full brightness, which contains significant blue light emissions. We also tested the use of the iPad with the app f.lux equipped, which reduces the blue light emissions, giving the iPad light a warmer coloring. In our tests of full brightness versus dim iPad use and of the app f.lux, we found no real differences between conditions.

As further context, the teens were required to hold the iPad 40 cm away from their face and had all white background content playing on the iPad. This was done to maximize the amount of bright screen light reaching their eyes. In the real-world use of iPads, teens are unlikely to do this. In addition, I own an iPad and rarely would use the full brightness setting. Therefore, our conclusion based on these data can be that 1 hour of iPad use before teens’ usual bedtime is okay.

Violent Video Games and Teen Arousal
To test how violent video games affect teens’ arousal, we evaluated 17 adolescents by providing them with 50 or 150 minutes of violent video game time before their usual bedtime.² Because this game had just come out in the stores, it was a novel experience for the teens, which should have added to the excitement and arousal.

In terms of arousal (measured via heart rate), we found no differences while the teens played video games or after they finished playing video games. Yet, they took longer to fall asleep after 150 minutes of video gaming versus the 50-minute condition. In addition, after 150 minutes of video-gaming, the teens got less sleep (particularly REM sleep, involved in consolidating learning and memory) and had poorer sleep quality. Although the teens’ sleep was affected, we could not determine that it was the result of physiological arousal.

Direct Cause and Effect?
In our 2010 study, a research priority was to prove a direct (rather than correlational) cause and effect between the sleep changes and the use of electronics. I review a lot of manuscripts in this field, and virtually all of them are correlational studies, which cannot determine cause and effect. As seen from the iPad and video game studies mentioned above, I’m interested in what mechanism is causing poor sleep as a result of technology use before bedtime.

It may seem intuitive, but our studies are pointing toward 50 to 60 minutes worth of electronics use being okay, even if the content is violent or on a bright screen. Yet, effects start being seen toward the 120- to 150-minute mark.

It’s important to begin to understand that technology use before bedtime is prevalent and inevitable. Efforts need to be focused on determining what levels of technology use before bed are safe.

To answer this, many more controlled laboratory studies are needed to understand the effects from various sources of technology use. There still is a long way to go, especially when the rate at which producers create new technologies exceeds the rate at which investigators can conduct and report on this research.

References
1. Cain N, Gradisar M. Electronic media use and sleep in school-aged children and adolescents: a review. Sleep Med.2010;11:735-742.
2. King DL, Gradisar M, Drummond A, et al. The impact of prolonged violent video-gaming on adolescent sleep: an experimental study. J Sleep Res. 2012 Nov 9. [Epub ahead of print.]