The Relationship Between State Boredom and Sleep–Wake Disruptions: A Mediation Model via Smartphone Addiction and Bedtime Procrastination

Bedtime procrastination is linked to poor sleep quality, daytime sleepiness, and altered sleep timing. Identifying the factors influencing this behavior is crucial. Among them, problematic smartphone use can delay bedtime. State boredom, a multidimensional concept (high and low arousal, disengagement, inattention, and time perception), triggers problematic smartphone use as a way to cope with boredom, resulting in delayed bedtime and sleep–wake issues. This study aimed to test mediation models where state boredom predicts sleep-related outcomes both directly and indirectly through smartphone addiction and bedtime procrastination. A total of 259 participants (138 women; mean age = 38.44 years) completed an online survey, including the Mini-Sleep Questionnaire, Bedtime Procrastination Scale, Mobile Addiction Scale, Multidimensional State Boredom Scale, and measures of sleep timing on workdays and free days. Results showed significant positive associations among all variables. Mediation analyses revealed that state boredom directly predicted poor sleep quality and daytime sleepiness, and indirectly predicted smartphone addiction and bedtime procrastination. Additionally, boredom indirectly influenced sleep timing via bedtime procrastination. Overall, the findings suggest that boredom can lead to problematic smartphone use, which in turn delays bedtime, resulting in poorer sleep quality, increased daytime sleepiness, and delayed sleep timing.