Objective: Our goal was to compare sleep quality characteristics in adults with and without SCT and ADHD, as well as to thoroughly investigate the SCT-factors and sleep association. Method: The study included 274 participants (age :18-35, 70.4% female).The Adult SCT Ratings Scale, the Adult ADHD Self-Report Scale (ASRS), and the Pittsburgh Sleep Quality Index were used. Results: We found four important results: Hyperactivity/Impulsivity and daydreaming significantly impacted sleep quality. Poor sleep quality negatively impacted daydreaming and sluggishness, but not as much as ADHD symptoms. Sleep Latency and Sleep Disturbances affected daydreaming. Gender differences: 1. Poor sleep quality increased daydreaming and sluggishness in women, but had no significant effect in men. 2. Hyperactivity/Impulsivity did not affect women’s daydreaming, but increased it in men. 3. SCT symptoms were not substantially affected by age in women, but sluggishness decreased with age in men. Conclusions: Our study is one of the first studies to reveal that the sct-sleep relationship can be bidirectional. Additionally, the relationship between SCT factors and sleep may differ, as in ADHD inattention and ADHD-HI.