Discrepancies Between Self-reported and Objectively Measured Smartphone Screen Time: Before and During Lockdown.

Area of Science:

• Public Health
• Behavioral Science
• Digital Health

Background:

• Screen time poses higher health risks than other sedentary behaviors.
• Social lockdowns can increase screen time, decrease physical activity, and alter time perception.

Purpose of the Study:

• To compare self-reported smartphone screen time (SR-SST) with objectively measured smartphone screen time (OM-SST).
• To analyze these differences in active and inactive Portuguese adults before and during a social lockdown.

Main Methods:

• Cross-sectional analysis of 211 Portuguese adults (aged 25.2 ± 8.5 years).
• Data collected from cohorts before and during a social lockdown.
• Smartphone screen time measured via self-report (SR-SST) and objective smartphone tracking (OM-SST).
• Physical activity (PA) was self-reported.
• Statistical analyses included linear regressions, Bland and Altman analysis, and T-tests.

Main Results:

• The lockdown cohort exhibited higher OM-SST (p < 0.001) and SR-SST (p = 0.009) compared to the pre-lockdown cohort.
• Before lockdown, no significant difference existed between SR-SST and OM-SST (p = 0.100).
• During lockdown, a good agreement (ICC = 0.72) was found, but participants underestimated OM-SST by ~71 min/day (p < 0.001).
• This underestimation was greater in inactive (~85 min/day) versus active (~49 min/day) individuals.

Conclusions:

• Individuals tend to underestimate their daily smartphone screen time, indicating a lack of awareness of this potentially harmful behavior.
• This underestimation is more pronounced during lockdowns and in inactive populations, increasing health risks.
• Findings offer crucial insights for policymakers to develop strategies for reducing population screen time from a preventive health standpoint.