London: Smartphone use directly correlates with sleep, with greater use demonstrating a significant association with shorter sleep duration and worse sleep efficiency, according to researchers at UC San Francisco.
Their study appears online Nov. 9, 2016, in PLOS ONE.
“Our study found that, not surprisingly, people spend a lot of time interacting with their phones,” senior author Gregory Marcus, MD, MAS, a UCSF Health cardiologist and director of clinical research in the UCSF Division of Cardiology, was quoted as saying by the university website.
“This was the first study to examine such use in a broad population, directly measuring screen time rather than relying on self-reported use. And, those with more screen time use had poorer sleep.”
About 64 percent of American adults owned a smartphone in 2015, and an estimated 68 percent of owners store their phone on a bedside table while sleeping. Screen time differs across age and race but is similar across socioeconomic groups.
Poor sleep – either quantity or quality – has been shown as a risk factor for obesity, diabetes, cardiovascular disease, depression and overall mortality. Light in the blue spectrum, such as that produced by a smartphone, can suppress production of melatonin, leading to decreased drowsiness, difficulty initiating sleep and non-restorative sleep, the authors said.
In their PLOS ONE study, Marcus and his colleagues used a volunteer sample of 653 people (average age 42) from the more than 23,000 individuals enrolled worldwide in the UCSF Health eHeart Study as of Sept. 1, 2015.
The ongoing Health eHeart Study, which currently includes nearly 80,000 consented participants toward a goal of 1 million, harnesses the power of online and mobile technology to gather cardiovascular data through devices such as smartphone apps, ECG smartphone cases and portable blood pressure cuffs.
The participants downloaded an app developed by Ginger.io for Android-based smartphones. The app recorded screen time continuously as the number of minutes in each hour the screen was on, as long as the phone was not in “airplane” mode and the app not turned off. Resulting data then was transmitted daily over the Internet to the study database.
Smartphone screen time was measured between Sept. 1, 2014, and Sept. 30, 2015. The total and average screen time was computed over selected 30-day windows for each participant.
India Blooms News Service
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