Exposure to smartphone screens is associated with lower sleep quality, according to a study published November 9, 2016 in the open-access journal PLOS ONE by Matthew Christensen from the University of California, San Francisco, USA, and colleagues.
Smartphones are increasingly becoming part of everyday life, but questions remain about the effects of frequent use on sleep. Poor sleep is associated with health conditions such as obesity, diabetes and depression.
Christensen and colleagues sought to test the hypothesis that increased screen-time may be associated with poor sleep by analyzing data from 653 adult individuals across the United States participating in the Health eHeart Study. Participants installed a smartphone application which recorded their screen-time, defined as the number of minutes in each hour that the screen was turned on, over a 30-day period. They also recorded their sleeping hours and sleep quality.
The researchers found that each participant totaled an average of 38.4 hours over this period, with smartphones being activated on average for 3.7 minutes in each hour. Longer average screen-time was associated with poor sleep quality and less sleep overall, particularly when smartphones were used near participants' bedtime.
The authors state that their study is the first to measure smartphone exposure prospectively, but caution that the study also had some important limitations, including the self-selection of study participants and self-reporting of data. While the authors' findings cannot show causation or exclude the "effect-cause" that poor sleep could lead to more screen time, the association they found could fit with the theory that bedtime smartphone use may negatively impact sleep.
In your coverage please use this URL to provide access to the freely available paper: http://dx.plos.org/10.1371/journal.pone.0165331
Citation: Christensen MA, Bettencourt L, Kaye L, Moturu ST, Nguyen KT, Olgin JE, et al. (2016) Direct Measurements of Smartphone Screen-Time: Relationships with Demographics and Sleep. PLoS ONE 11(11): e0165331. doi:10.1371/journal.pone.0165331
Funding: Research reported in this publication was supported by the Office of Behavioral Social Sciences (OBSSR), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institute of Neurological Disorders and Stroke (NINDS), National Heart Lung and Blood Institute (NHLBI), and National Institute on Alcohol Abuse and Alcoholism (NIAAA) of the National Institutes of Health under award number 1U2CEB021881 (https://grants.nih.gov/grants/oer.htm). MAC is a research fellow supported by the Sarnoff Cardiovascular Research Foundation (http://sarnofffoundation.com). KTN is a fellow supported by National Institute on Minority Health and Health Disparities (NIMHD) under award number R25MD006832 (http://www.nimhd.nih.gov/). Ginger.io Incorporated (https://ginger.io) provided support in the form of salaries for authors LK and STM, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors (LK, STM) are articulated in the 'author contributions' section. The other funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: LK and STM are employees of Ginger.io Incorporated. This does not alter our adherence to PLOS ONE policies on sharing data and materials.