Abstract
The alteration in circadian typology and insomnia were prevalent among both Individuals with IGD and those with attention deficit hyperactivity disorder (ADHD), the most comorbid psychiatric disorder of IGD. This study aimed to evaluate the relationships between circadian typologies, insomnia, and internet gaming disorder (IGD) and how ADHD affects this relationship. We recruited three groups of 69 young adults: an IGD group, a control group comprising age- and sex-matched nongamers, and a group of gamers without IGD through diagnostic interviews. The participants with IGD exhibited lower composite scale of morningness (CSM) scores and thus a higher eveningness preference In addition, the score of Pittsburgh insomnia rating scale-20-item version (PIRS_20) was significantly higher among those with IGD. The participants with IGD and ADHD exhibited lower CSM scores but higher PRIS_20 scores than the participants with IGD but without ADHD. The present findings indicate that participants with IGD exhibited a tendency of eveningness preference and experienced more severe insomnia. ADHD exacerbated the eveningness preference and insomnia of individuals with IGD. Close attention should be paid to sleep problems in individuals with IGD, particularly to those with ADHD.