Sleep and ADHD

The prevalence picture

Sleep problems are reported by ~50–75% of adults with ADHD across the literature (Hvolby 2015¹ review). Any sleep complaint runs ~70–80% in adult ADHD samples per the 2019 European Consensus; clinically significant insomnia ~50–70%; delayed sleep phase syndrome (DSPS) specifically 73–78% per Bijlenga 2019. Restless legs syndrome is elevated (Cortese et al. 2013⁸ meta-analysis). Sleep apnoea is elevated and a known ADHD-mimic; the National Institute for Health and Care Excellence (NICE) guideline NG87 treats it as part of standard medical mimic rule-out.

Sleep should be assessed as part of standard adult ADHD evaluation, not as a separate complaint that emerges later.

Delayed sleep phase disorder — the dominant pattern

DSPS is a circadian-rhythm sleep-wake disorder characterised by chronic delay of sleep onset and wake time relative to desired or required times. Sleep itself is normal when the patient sleeps on their preferred (delayed) schedule; the impairment comes from the misalignment with social and work demands. Bijlenga et al. 2019² systematic review put prevalence in adult ADHD at 73–78% versus 0.13–3% in the general population. The over-representation is large enough that DSPS should be a default consideration in adult ADHD sleep complaints.

The mechanism is delayed dim-light melatonin onset (DLMO). van der Heijden et al. 2005³ and subsequent work documented that ADHD adults with sleep onset problems show DLMO delayed by ~1.5–2 hours relative to controls. The biological sleep-onset window is shifted later. Asking the reader to fall asleep at 11pm when their DLMO is at 1:30am is asking them to override a biological clock, not to demonstrate better hygiene. The intervention has to move the circadian phase, not the bedtime schedule. The morning side is covered at morning routine collapse.

Onset, fragmentation, and total sleep time

Beyond DSPS, adult ADHD shows broader sleep architecture differences (Hvolby 2015; Bijlenga 2019). Sleep onset latency often runs 30+ minutes versus 10–20 in matched controls. Sleep fragmentation — more frequent nocturnal awakenings, lower sleep efficiency — is consistent. Total sleep time runs ~30–60 minutes shorter than matched controls; the deficit accumulates across the work week. Subjective sleep quality is consistently rated worse than objective polysomnography would suggest; the experience of unrefreshing sleep is real even when sleep architecture is partially preserved. Restless legs syndrome (Cortese 2013) treatment — iron repletion if ferritin under 50, dopaminergic agonist if needed — can substantially improve sleep in the RLS-positive subset.

The stimulant-sleep interaction

Stimulants delay sleep onset for many adults; some adults sleep better on stimulants because untreated ADHD-related cognitive racing and emotional dysregulation otherwise prevent sleep. Kidwell et al. 2015⁷ meta-analysis pooled the youth data; adult data is consistent. The honest framing: timing and dose matter. Afternoon long-acting doses (extended-release amphetamine at 11am) frequently produce sleep-onset problems regardless of subjective alertness at bedtime. Moving the first dose earlier by 60–90 minutes often shifts sleep onset meaningfully without changing the dose.

Low-dose melatonin — the dose and timing that matter

The most well-evidenced ADHD-specific sleep intervention. van der Heijden et al. 2007⁴ ran a paediatric trial in ADHD kids with chronic sleep-onset insomnia: 0.05 mg/kg melatonin advanced sleep onset by about 26 minutes vs placebo over 4 weeks. van Andel et al. 2022⁵ ran the adult version in delayed sleep phase, combining melatonin (0.5 mg) with morning bright light therapy and a stable sleep schedule: clear circadian shift and improved sleep.

Two things the article is specific about. Dose: 0.5–1 mg in adults. The standard US OTC dose (3 mg, 5 mg, 10 mg) is supraphysiological; Brzezinski et al. 2005⁶ pharmacokinetic work showed 0.3–1 mg produces serum concentrations matching the endogenous nocturnal peak. Higher doses do not produce better outcomes and may produce hangover-style next-day sedation. Timing: 1–2 hours before desired sleep onset, not at bedtime. Melatonin functions here as a phase-shifting signal, not a sedative.

CBT-I — first-line, under-delivered

Cognitive behavioural therapy for insomnia (CBT-I) is first-line treatment for chronic insomnia in American Academy of Sleep Medicine (AASM) guidelines. The 2024 SHARI trial and van Veen 2022 group on CBT-I for adult ADHD with DSPS show transferability with positive results. Adult ADHD-specific delivery is limited; the evidence supports applicability. Sleep-restriction therapy, stimulus control, cognitive components targeting catastrophic insomnia beliefs — all transferable.

Sleep hygiene’s limits

Dark room, cool temperature, no screens, consistent schedule, no caffeine after noon. Necessary but not sufficient for adults with ADHD-related DSPS. Most readers have tried it. Recommending hygiene as primary intervention treats a symptom of circadian phase shift as a behavioural problem. The honest framing: hygiene is the floor, not the ceiling. What does help is anchoring on wake time rather than bedtime — the body clock responds to wake time more consistently — plus morning light exposure in the first hour after waking (outdoor light or 10,000 lux lamp) to advance the circadian phase.

Cannabis for sleep — community-strong, longitudinally costly

Community signal is strong; many ADHD adults use cannabis nightly for sleep onset. Short-term sleep-onset effect is real (CB1 receptor effects on arousal). Longitudinal costs are documented: tolerance, dependence, reduced REM sleep, withdrawal-driven insomnia on discontinuation, and broader concerns about cannabis-ADHD interaction. Cross-link to ADHD and alcohol for the substance-and-ADHD framework. The article names the pattern without moralising; the cost data is real.