Smartphone ownership and screen time are increasing across the world, but there have been few attempts to quantify smartphone addiction on a global scale. We conducted a meta-analysis of studies published between 2014 and 2020 that used the Smartphone Addiction Scale, the most common measure of problematic smartphone use. This scale measures whether smartphone use interferes with one’s daily life. We focused on studies of teenagers and young adults (aged 15 to 35) since they show the highest screen time and smartphone ownership rates. Across 85 samples, 24 countries, and 39,292 participants, we demonstrate that problematic smartphone use is increasing across the world. China, Saudi Arabia, and Malaysia had the highest scores while Switzerland, Germany, and France had the lowest. Our results provide global norms for researchers and can help identify countries that could benefit from targeted interventions.

Problematic smartphone use is rising across the world and has been associated with reductions in concentration and well-being. Few interventions aiming to reduce smartphone use take a multi-faceted approach that balances feasibility and effectiveness. We developed such an intervention with ten simple guidelines that nudge users to reduce their screen time (e.g., disabling non-essential notifications). Two pre-registered studies tested the intervention. Study 1 (N = 51) found reductions in screen time, problematic smartphone use, and depressive symptoms after two weeks. Study 2 (N = 70) found that the intervention caused larger changes in screen time, problematic smartphone use, and sleep quality than a control group of screen time monitoring alone. Our brief intervention reduced screen time by one hour per day and returned problematic smartphone use scores to normal levels for at least six weeks. This intervention provides simple, scalable, and feasible behavioural guidelines to promote healthy technology use.