Demographic predictors of bedtime procrastination in the Japanese population

Purpose Bedtime procrastination (BP) is a prevalent and problematic phenomenon in the general population. However, no study on BP has been conducted in Japan, where people sleep the least in the world. The current study developed the Japanese version of the Bedtime Procrastination Scale (BPS) and investigated the relationship between BP, demographic features, and sleep outcomes in a population with a wide range of demographics. Methods To investigate BP in Japan, we developed the Japanese version of the BPS and assessed its internal consistency, test-retest reliability, factor structure validity, construct validity, and criterion-related validity in two samples (N= 252 and N=630). We also investigated the relationship between BP and demographic features (gender, age, and employment status) and sleep outcomes (Athens Insomnia Scale, sleep hours, sleep onset latency, and sleep efficiency). Results: The BPS showed good internal consistency, test-retest reliability, and factor structure, construct, and criterion-related validity. Moreover, BPS scores were moderately higher for younger participants than for those in their 40s and older, slightly higher for females than for males, and non-significantly different between the employment statuses. Conclusions This study provides new data on demographic predictors of BP in the Japanese population, which is characterized by short sleep duration. Although there were no clear effects of gender and employment status on BP, age was a relatively strong predictor of BP in the Japanese population. Particularly, individuals in the younger age groups had a higher BP risk than those in the older age groups. This finding warrants further studies targeted at young individuals.