Why do people with ADHD have trouble falling asleep?
Many people with ADHD struggle to fall asleep, even when they feel exhausted. According to recent Frontiers in Psychiatry reviews and NHS guidance, these difficulties are not simply about poor bedtime habits. They often result from a combination of biological, behavioural, and medication-related factors.
The science behind ADHD and sleep
Research shows that many individuals with ADHD have a delayed circadian rhythm, meaning their body’s internal clock naturally runs later than average. Studies in Frontiers in Psychiatry (2025) found later melatonin release and variations in “clock genes” that shift the natural sleep–wake cycle. This helps explain why people with ADHD often feel most alert late at night, even when they need to wake up early. ADHD also affects dopamine and norepinephrine regulation, the same brain chemicals involved in alertness and attention. When these systems are dysregulated, the brain can stay in a state of hyperarousal, making it harder to switch off and fall asleep.
Everyday factors that make it worse
Beyond biology, everyday routines can intensify sleep problems. According to NHS advice, screen use before bed, inconsistent sleep schedules, and stimulant medication taken too late in the day can all delay sleep. Many adults describe racing thoughts or a restless mind at night, a hallmark of ADHD-related hyperactivity that does not stop when the lights go out.
Evidence from BMJ Mental Health (2025) suggests that up to 85 per cent of adults with ADHD experience insomnia or significant sleep disruption, compared with around 30 per cent of the general population.
What helps
NICE guideline NG87 recommends starting with behavioural and environmental strategies such as consistent bedtimes, limiting screens, using calming bedtime routines, and improving overall ADHD management. Cognitive behavioural therapy for insomnia (CBT-I), bright-light therapy, and morning activity can also help reset the body clock.
For some people, clinicians may consider melatonin under medical supervision. NHS guidance emphasises that it should be tailored and reviewed regularly. Adjusting the timing of stimulant medication may also reduce night-time wakefulness.
Private services such as ADHD Certify provide structured ADHD assessments and post-diagnostic reviews, helping adults and children better understand how ADHD symptoms, including sleep issues, affect their daily life.
The takeaway
Sleep difficulties are one of the most common yet overlooked aspects of ADHD. Understanding the biological roots and applying consistent, evidence-based habits can make a real difference. If sleep problems persist, it is best to speak with a GP or specialist to review medication timing, explore behavioural therapies, or rule out other sleep disorders.
