Abstract
The current study used device-logged screen-time records to measure week-to-week within-person associations between stress and smartphone use in undergraduate students (N = 187; mean age = 20.1 years). The study was conducted during fall 2020 and focused on differences across types of app used and whether accumulated screen use each week predicted end-of-week mood states. Participants uploaded weekly screenshots from their iPhone "Screen Time" settings display and completed surveys measuring stress, mood, and COVID-19 experiences. Results of multilevel models showed no week-to-week change in smartphone hours of use or device pickups. Higher stress levels were not concurrently associated with heavier smartphone use, either overall or by type of app. Heavier smartphone use in a given week did not predict end-of-week mood states, but students who tended to spend more time on their phones in general reported slightly worse moods-a between-persons effect potentially reflecting deficits in well-being that are present in students' off-line lives as well. Our findings contribute to a growing scholarly consensus that time spent on smartphones tells us little about young people's well-being.