BACKGROUND: We examined whether current overall attention deficit hyperactivity disorder (ADHD), inattention, or hyperactivity symptom severities are associated with the current presence and persistent history of sleep problems. METHODS: N = 942 participants of the Netherlands Sleep Registry filled out online several validated questionnaires. Regression analyses were performed to assess the association between (1) current overall ADHD symptom severity and the current presence of sleep problems, (2) current ADHD symptom-severity groups and the persistent history of sleep problems, and (3) current inattention or hyperactivity symptom severities and the current presence of sleep problems. RESULTS: (1) Current overall ADHD symptom severity was associated with the odds of suffering from probable obstructive sleep apnea syndrome (OSAS), restless legs syndrome (RLS), periodic limb movement disorder (PLMD), insomnia disorder (ID) with predominant difficulties initiating sleep (DIS) and maintaining sleep (DMS), but not with the odds of suffering from narcolepsy or ID with predominant early-morning awakening (EMA). Current overall ADHD symptom severity was also associated with an extreme evening chronotype but not with short sleep. (2) The group with the most severe current ADHD symptoms was more likely to have a history of persistent OSAS, RLS, and ID. (3) The severity of symptoms of hyperactivity, but not of inattention, was specifically associated with probable RLS, PLMD, ID with DIS or DMS, and short sleep. Inattention symptom severity was only related to the probability of being an extreme evening chronotype. CONCLUSION: ADHD severity, especially the severity of hyperactivity, is associated with the current presence and persistent history of sleep problems.