ADHD and Insomnia: Why Your Brain Won’t Let You Sleep
Read time: 13–15 minutes
What you’ll learn:
- Why ADHD and insomnia co-occur at rates 2–4 times higher than the general population
- The three neurobiological mechanisms behind ADHD-related sleep problems
- How insomnia worsens ADHD symptoms, and why treating your sleep can improve both
- What CBT-I does differently from sleep hygiene, and why it works for ADHD-related insomnia
You’ve been a night owl your whole life. Not by preference. Your brain simply won’t wind down at a reasonable hour. While other people seem to drift off without much effort, you lie there at midnight with a mind that’s running at full speed, cataloguing tomorrow’s tasks, replaying conversations, jumping between ideas that feel urgent and completely irrelevant in equal measure.
You’ve tried going to bed earlier. You’ve cut the screens, cooled the room, done the breathing exercises. Some of it helps at the margins. None of it solves the problem. By the time your body finally gives up sometime after 1 a.m., you’ve lost two or three hours you were never going to get back, and you wake up with a deficit that colours the entire next day.
If you were diagnosed with ADHD as an adult, or if you’re starting to wonder whether ADHD explains a pattern you’ve never quite been able to account for, there’s a reasonable chance the sleep difficulty isn’t separate from that picture. It’s part of the same neurobiology.
That doesn’t mean you’re stuck with it.
How common is the overlap?
Research consistently finds that 40–70% of adults with ADHD experience insomnia symptoms, more than double the rate in the general population (Uygur, 2025). When researchers apply formal diagnostic criteria rather than self-report, 44.4% of adult ADHD patients meet the full DSM-5 threshold for insomnia disorder (Adamou et al., 2021). Women with ADHD face a particularly pronounced gap: insomnia prevalence of 43.9% compared to 12.2% in women without ADHD, according to researchers at McGill University’s Douglas Research Centre (Wajszilber et al., 2018).
A 2024 study from the Netherlands (the largest adult ADHD sleep sample to date, drawing on data from 3,691 patients) confirmed that sleep problems and ADHD severity are bidirectionally associated: each makes the other worse (van der Ham et al., 2024).
These aren’t people who simply stay up too late by choice. The mechanisms run deeper.
Three reasons the ADHD brain struggles at night
Your body clock is running late
Most people’s bodies begin releasing melatonin, the hormone that signals that biological night has begun, around 9 to 10 p.m. In adults with ADHD, that signal arrives approximately 90 minutes later (Fabiano, 2025). Children with ADHD show a delay of around 45 minutes. This isn’t a metaphor for preferring evenings. It’s a measurable shift in the dim-light melatonin onset (DLMO) confirmed across multiple studies using objective biological markers.
The result: up to 78% of adults with ADHD exhibit a delayed sleep-wake cycle. The body clock that governs when you feel sleepy, when your core temperature drops, when cortisol rises in the morning, is running roughly an hour and a half behind the schedule that society expects you to keep.
Sleep-onset insomnia in this context isn’t a habit problem. When you force yourself to lie down at 10:30 p.m. because you need to be up at 6:30, you’re asking your body to sleep before its biological night has started. The fact that you can’t is not a failure of willpower or sleep hygiene. It’s a timing mismatch.
This matters for treatment. Generic advice to “go to bed earlier” doesn’t address a phase-delayed circadian clock. It just creates more time lying in a dark room feeling frustrated.
The arousal system doesn’t downshift
ADHD involves dysregulation of dopamine, a neurotransmitter that does far more than manage reward and motivation. Dopamine is also deeply involved in regulating sleep-wake states and arousal. In the ADHD brain, this system tends to stay activated later into the evening, generating what researchers call nighttime hyperarousal: heightened cognitive activity at the very time the brain is supposed to be decelerating.
A 2025 study published in Scientific Reports put a finer point on this. Researchers at the University of Birmingham found that the link between ADHD traits and sleep quality was fully mediated by pre-sleep cognitive arousal: the tendency to experience an active, busy mind in the period before sleep (Smullen et al., 2025). The racing thoughts that keep you awake aren’t incidental to ADHD; they’re a direct expression of how the ADHD brain regulates (or fails to regulate) its own activity at night.
The same paper noted that cognitive arousal is reported roughly ten times more frequently than somatic arousal in people with insomnia. This matters: most common relaxation advice (breathing exercises, muscle relaxation, warm baths) targets the body. The ADHD sleeper’s primary problem is happening in the mind.
Insomnia develops its own momentum
This is where sleep difficulty becomes self-sustaining.
In the early stages, ADHD-related circadian delay and cognitive arousal make sleep hard to initiate. Over weeks and months, two additional layers develop. The first is conditioned arousal: the bed itself becomes associated with wakefulness and frustration, gradually shifting from a cue for sleep into a cue for alertness. The second is performance anxiety about sleep, the worry about whether tonight will be another bad night, which generates exactly the kind of cognitive arousal that delays sleep further.
The 3P model of insomnia (predisposing, precipitating, perpetuating factors) describes this well. ADHD functions as a predisposing factor: it raises baseline vulnerability. A period of stress, a schedule change, or a medication adjustment can act as a precipitating factor. But it’s the perpetuating factors (conditioned arousal, sleep performance anxiety, irregular sleep schedules) that turn a rough patch into chronic insomnia.
This distinction is not merely academic. It’s the reason insomnia doesn’t automatically resolve when ADHD symptoms are better managed. The perpetuating cycle has its own logic, and it requires its own targeted intervention.
It runs both ways
Insomnia doesn’t just follow from ADHD. It feeds back into it.
Sleep deprivation compromises exactly the cognitive functions that ADHD already taxes most heavily: sustained attention, working memory, impulse control, and emotional regulation. A night of poor sleep doesn’t produce a neutral baseline for someone with ADHD; it produces a compounded deficit. Daytime ADHD symptoms worsen. Executive function declines further. The capacity to implement the routines that might improve sleep the following night is itself diminished.
This is what researchers mean when they describe ADHD and insomnia as bidirectionally associated. More severe ADHD symptoms predict worse insomnia; worse insomnia predicts more severe ADHD symptoms (Uygur, 2025). The relationship spirals in both directions.
The practical implication points in a useful direction: addressing insomnia directly, not as a secondary concern to be resolved after ADHD treatment stabilises, produces measurable benefits in both sleep and ADHD functioning. The bidirectional relationship means improvement flows both ways.
Not all sleep problems in ADHD are the same
Before discussing treatment, one important clarification.
Not every sleep difficulty in adults with ADHD is insomnia in the classical sense, and not every sleep difficulty responds to the same intervention. Two conditions in particular are worth knowing about.
Restless legs syndrome (RLS) is characterised by an uncomfortable urge to move the legs, typically worse at rest and in the evening. It affects approximately 30% of adults with ADHD, compared to about 2% of the general population (managing comorbid sleep issues, 2025). RLS has a neurological basis distinct from insomnia, and it requires its own assessment and treatment.
Obstructive sleep apnoea (OSA) involves repeated breathing interruptions during sleep. It affects 20–30% of adults with ADHD, compared to roughly 3–5% of the general population. OSA causes fragmented, unrestorative sleep that can closely mimic insomnia symptoms and worsen ADHD cognitive impairment. It is treated with airway management (CPAP or similar), not behavioural sleep intervention.
If you snore loudly, wake frequently gasping or choking, have been told you stop breathing during sleep, or if your daytime sleepiness is severe and unrelenting despite time in bed, it’s worth raising this with your GP before assuming the problem is insomnia. Cognitive-behavioural therapy for insomnia (CBT-I) addresses the perpetuating cycle of insomnia; it doesn’t treat disordered breathing or movement-related sleep disruption.
A note on medication and sleep
Stimulant medications, the most commonly prescribed ADHD treatments, can affect sleep, and many adults with ADHD experience this directly. Stimulants increase dopamine and norepinephrine availability, which promotes wakefulness. Taken late in the day, or at doses that extend well into the evening, they can delay sleep onset. This is a real effect, and it’s worth discussing with the prescriber who manages your ADHD medication.
What stimulants generally do not do is create chronic insomnia from scratch. The predisposing factors (circadian phase delay, arousal dysregulation) are present in ADHD independently of medication. And once chronic insomnia is established, adjusting medication timing rarely resolves it, because the conditioned arousal and sleep performance anxiety are now operating on their own.
This means medication management and insomnia treatment are largely parallel tracks. Getting one right doesn’t substitute for the other. If your sleep has been difficult for months or years, that’s a problem with perpetuating factors, and those factors respond to a targeted behavioural and cognitive intervention regardless of what you take or when.
What helps: the case for CBT-I
Cognitive Behavioural Therapy for Insomnia (CBT-I) is the first-line treatment for chronic insomnia across clinical guidelines internationally, including for insomnia that co-occurs with other conditions. A 2025 systematic review in the Journal of Sleep Research examined the evidence specifically in neurodevelopmental populations, finding short-term effectiveness of CBT-I in adults with ADHD across the available studies (Cullen et al., 2025).
CBT-I works by targeting the perpetuating factors that maintain chronic insomnia. The components that carry the most weight are stimulus control, which systematically breaks the association between bed and wakefulness, and sleep restriction, which consolidates fragmented sleep and rebuilds sleep drive. These two components address the conditioned arousal layer that develops once insomnia has been established, regardless of what originally caused the sleep disruption.
Cognitive components address the sleep performance anxiety and dysfunctional beliefs about sleep that develop as secondary perpetuating factors. The racing thoughts that characterise pre-sleep cognitive arousal in ADHD are a particular focus: the goal isn’t to silence them (which doesn’t work and increases arousal through effort) but to change the relationship to them, reducing their capacity to delay sleep onset.
The ADHD context shapes how some of these components are implemented in practice. Daily sleep diaries, a standard CBT-I tool, require consistency that can be difficult for many adults with ADHD; brief retrospective formats tend to be more workable than real-time logging. A fixed wake time, one of CBT-I’s most potent circadian regulators, is also one of the more demanding components for someone whose body clock is running 90 minutes late. These adaptations are worth discussing explicitly with a specialist rather than assuming standard protocols will fit without modification.
What CBT-I does not address is the circadian phase delay itself. For adults with ADHD whose primary difficulty is sleep onset at a conventionally early hour rather than a sustained inability to sleep, the circadian component may warrant additional strategies (morning light exposure, evening light restriction, appropriately timed low-dose melatonin) alongside CBT-I. A specialist assessment helps distinguish which elements of the sleep problem are circadian in origin and which are maintained by the classic insomnia perpetuating cycle.
A word on sleep hygiene. Sleep hygiene (consistent schedules, cool rooms, limited caffeine, no screens before bed) is genuinely useful, but it operates at the level of sleep opportunity, not the perpetuating cycle. For someone with garden-variety poor sleep, hygiene adjustments can make a meaningful difference. For someone with established chronic insomnia, whether ADHD is in the picture or not, hygiene is a supporting layer. It doesn’t touch conditioned arousal. It doesn’t address cognitive hyperarousal. It doesn’t consolidate fragmented sleep drive. CBT-I addresses all three. The two aren’t in competition: hygiene forms the foundation, and CBT-I builds the structure on top of it.
If you’ve tried every sleep hygiene recommendation and found limited benefit, that’s not a personal failing. It reflects the level at which hygiene operates relative to the problem you have.
What to do next
ADHD-related insomnia is genuinely complex. It involves a neurobiological predisposition that no amount of willpower resolves, and a self-sustaining perpetuating cycle that requires targeted intervention. The evidence base for treating that cycle with CBT-I is solid and growing.
If your sleep has been disrupted for three months or more, if you’re spending substantial time awake in bed, if the difficulty is affecting your daytime functioning: these are the markers of chronic insomnia, and they warrant a structured approach rather than continued trial and error with hygiene tips.
A free 15-minute consultation with BC CBT-I is a low-investment way to clarify whether CBT-I is the right fit for your situation. You’ll come away with a clearer picture of what’s driving your sleep difficulty and what a treatment course would look like.
Book a free 15-minute consultation →
TL;DR
- How common is it? 40–70% of adults with ADHD experience insomnia symptoms. 44.4% meet formal diagnostic criteria for insomnia disorder. Women with ADHD are disproportionately affected.
- Why does the ADHD brain struggle at night? Three overlapping mechanisms: a biological body clock running ~90 minutes late (delayed DLMO), dopamine-related arousal dysregulation that keeps the mind active at night, and a self-sustaining perpetuating cycle (conditioned arousal, sleep anxiety) that develops once insomnia is established.
- Does insomnia worsen ADHD? Yes, bidirectionally. Sleep deprivation compounds exactly the deficits ADHD already taxes most: attention, executive function, emotional regulation. Treating insomnia produces measurable gains in ADHD functioning.
- What about RLS and sleep apnoea? Both are substantially more prevalent in ADHD than in the general population and require their own assessment. If disordered breathing or restless legs is part of the picture, a GP referral is the first step.
- What does CBT-I do? It targets the perpetuating factors maintaining chronic insomnia (conditioned arousal, sleep performance anxiety, irregular sleep timing) regardless of what originally triggered the problem. The ADHD context shapes how some components are delivered, but not the core treatment logic. Sleep hygiene is a useful foundation; CBT-I addresses what hygiene cannot.
About the author
Graeme Thompson, MA, RCC is a Registered Clinical Counsellor (BCACC #21951) and CBT-I specialist practising virtually across British Columbia. BC CBT-I is a specialist insomnia practice. CBT-I is the only treatment offered, applied across the full range of presentations including ADHD-related, anxiety-related, medication-related, and menopause-related insomnia.
Learn more about the practice →
References
Adamou, M., Hesdorffer, D. C., & Lambe, E. (2021). Insomnia disorder in adult attention-deficit/hyperactivity disorder patients: Clinical, comorbidity, and treatment correlates. Frontiers in Psychiatry, 12, 663889. https://doi.org/10.3389/fpsyt.2021.663889
Cullen, M., McCrory, S., Hooman, G., Coyle, M., & Fleming, L. (2025). Effectiveness of cognitive behavioural therapy for insomnia (CBT-I) in individuals with neurodevelopmental conditions: A systematic review. Journal of Sleep Research, 34(5), e70058. https://doi.org/10.1111/jsr.70058
Fabiano, N. (2025). ADHD as a circadian rhythm disorder: Evidence and implications for chronotherapy. Frontiers in Psychiatry, 16, 1697900. https://doi.org/10.3389/fpsyt.2025.1697900
Smullen, D., Kolodny, T., Bagshaw, A. P., & Mevorach, C. (2025). Pre-sleep arousal as a possible mechanism driving sleep problems in relation to ADHD traits. Scientific Reports, 15, 24554. https://doi.org/10.1038/s41598-025-09866-3
Uygur, H. (2025). Unraveling the insomnia puzzle: Sleep reactivity, attention deficit hyperactivity symptoms, and insomnia severity in ADHD patients. Frontiers in Psychiatry, 15, 1528979. https://doi.org/10.3389/fpsyt.2024.1528979
van der Ham, M., Bijlenga, D., Böhmer, M., Beekman, A. T. F., & Kooij, J. J. S. (2024). Sleep problems in adults with ADHD: Prevalences and their relationship with psychiatric comorbidity. Journal of Attention Disorders, 28, 1642–1652. https://doi.org/10.1177/10870547241284477
Wajszilber, D., Santiseban, J. A., & Gruber, R. (2018). Sleep disorders in patients with ADHD: Impact and management challenges. Nature and Science of Sleep, 11, 1–17. https://doi.org/10.2147/NSS.S163074