JMIR Publications

ABSTRACT

Background:

The impact of smartphone use on sleep remains intensely debated. Most existing studies used self-reported smartphone use data. Moreover, few studies have simultaneously examined associations of both smartphone addiction and objectively measured smartphone use with sleep, and the dose-response relationship between smartphone use and sleep risk has been consistently overlooked, requiring systematic and further research on this topic.

Objective:

To examine the associations of smartphone addiction and objectively measured smartphone use with sleep quality and duration.

Methods:

This cross-sectional study enrolled 17,713 participants from a university in China. We assessed objective smartphone screen time and unlocks by collecting screenshots of use records, and measured smartphone addiction using a validated questionnaire. Sleep quality and duration were estimated via the Pittsburgh Sleep Quality Index. Binary logistic regression, linear regression, and restricted cubic splines (RCS) regression models were used for the analyses.

Results:

2,533 participants (14.3%) met the criterion for poor sleep, with a mean (SD) sleep duration of 507.1(103.2) minutes/night. Notably, university students with smartphone addiction exhibited 184% higher risk of poor sleep(OR=2.84; 95%CI: 2.59 to 3.11) and 15.47 minutes shorter nighttime sleep duration (β=-15.47; 95%CI: -18.53 to -12.42) compared to those without smartphone addiction. Regarding objectively measured smartphone use, participants with ≥63 hour/week of smartphone screen time had 22% higher odds of poor sleep(OR=1.22; 95%CI: 1.08 to 1.37) and 6.66 minutes shorter nighttime sleep duration (β=-6.66; 95%CI: -10.19 to -3.13) compared to those with 0–21 hour/week, while those with 21~42 hour/week of smartphone screen time had 5.47 minutes longer nighttime sleep duration (β=5.47; 95%CI: 1.28 to 9.65). Similarly, compared to those with 0–50 times/week, participants with ≥400 times/week smartphone unlocks showed 61% higher odds of poor sleep(OR=1.61; 95%CI: 1.41 to 1.85) accompanied by 4.09 minutes shorter nighttime sleep duration (β=-4.09; 95%CI: -8.08 to -0.09), while those with 50~150 times/week of unlocks had 5.84 minutes longer sleep duration (β=5.84; 95%CI: 2.32 to 9.36). An inverted U-shaped association between objectively measured smartphone screen time and sleep duration was observed(P for non-linearity＜.001).

Conclusions:

Smartphone addiction, excessive objectively measured smartphone screen time, and unlocks are associated with both sleep quality and duration. RCS analyses revealed nuanced different dose-response relationships, with an inverted U-shaped association observed between smartphone screen time and sleep duration.