A new study billed as the first of its kind is adding fuel to the growing body of research linking heavy smartphone use to poorer sleep.
For the first time ever, researchers actually used smartphones to measure screen time and confirm its impact on a good night’s rest, instead of solely relying on self-reporting by participants.
“This is the first study to directly measure actual screen time in natural environments and compare it to sleep quality,” said senior author Dr. Gregory M. Marcus of the University of California, San Francisco.
“We did not rely on participant self-report, but rather utilized a mobile app that ran in the background and could capture exact screen time duration.”
Researchers examined data on 653 adults who took part in the online Health eHeart Study, wherein participants’ smartphones were provided with an app that recorded the number of minutes that the phone screen was on over the course of 30 days. Some participants reported what time they went to sleep and how long they slept, along with personal demographics and medical information.
The total screen time averaged 38.4 hours per 30 days, and average screen time per hour was 3.7 minutes. This comes out to one hour and 29 minutes per day, according to the report that was published in the journal PLoS ONE.
Among the 136 participants who gave information about their sleeping tendencies, the researchers discovered that increased screen time informed decreased sleep quality, a shorter amount of sleep time and a longer amount of time needed to fall asleep.
Screen time close to bedtime was found to be particularly linked to lower sleep efficiency and longer time needed to fall asleep, suggesting that "the relationship between overall smartphone use and sleep may be driven by exposure near bedtime," according to researcher Matthew Christensen.
“More screen time right around participant-reported bedtime was particularly associated with longer sleep latency (or a longer time to fall asleep) and reduced sleep quality,” Marcus said.
While Marcus said the light given off by smartphones could be suppressing the production of melatonin (which is related to sleep), he added that “it is also possible that engrossing activities that result in stimulation, such as following the latest post on Facebook or a bothersome tweet, might be counter to productive sleep preparation.”
Banner photo by Marcos Mesa Sam Wordley/Shutterstock.