A Longitudinal Investigation on the Reciprocal Relationship of Problematic Smartphone Use with Bedtime Procrastination, Sleep Quality, and Mental Health Among University Students.

Background: Problematic smartphone use (PSU) is linked to various mental health issues, but the relationship between PSU, bedtime procrastination, and mental health symptoms is unclear. Sleep factors related to PSU and its mental health effects have been understudied. This study explores the longitudinal associations between PSU, bedtime procrastination, sleep quality, and mental health in university students.