The biological clock is often delayed in ADHD, and stimulants may move it later still
STUDY: Hanshaw A et al, Front Pharmacol 2026
STUDY TYPE: Narrative review
FUNDING: National Institutes of Health (NCCIH)
Background
Amphetamine-based stimulants improve attention through dopamine and norepinephrine, but those pathways also raise arousal and can cause insomnia, worsening the delayed sleep-onset that is common in ADHD. This narrative review explores the dilemma.
Summary
Teens and young adults tend to have delayed sleep, and this is even more common in ADHD. They have delayed melatonin release and irregular cortisol rhythms. Nighttime light pushes sleep later, and amphetamines can exacerbate it further. In the worst case, this creates a vicious cycle where poor sleep leads to worse concentration and higher stimulant dosing. The authors speculate that sleep disruption may be one of the ways that amphetamines cause psychosis and mania. That mechanism isn’t proven, but we do know that amphetamines are associated with a greater risk of psychosis and mania than methylphenidate-based stimulants.
Higher doses, evening dosing, and extended-release formulations lead to more insomnia. But this isn’t always the case. ADHD itself can keep people up at night, through restless legs and restless minds. Longitudinal data on lisdexamfetamine found that sleep quality holds steady or improves over time, likely because better-controlled ADHD symptoms mean less bedtime hyperactivity. Overall, methylphenidate has more robust evidence to improve sleep — or at least not harm it — in ADHD than amphetamines. Clonidine and guanfacine are even more sleep-friendly.
Besides increasing arousal, amphetamines delay the circadian clock. The mechanisms include direct effects of dopamine and norepinephrine in the locus coeruleus and alterations in expression of circadian “CLOCK” genes.
Practice Implications
- Ask patients with ADHD about their sleep patterns. Are they sleep deprived on weekdays and oversleep on weekends (that’s social jet lag, a common cause of cognitive and mood problems in night owls)
- Look for stimulant effects, and consider a dawn simulator and night-time dark therapy to improve sleep in night owls.
—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
