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A December 2025 perspective in Frontiers in Psychiatry reviews evidence that a substantial subgroup of people with ADHD has delayed circadian timing and related sleep problems. It proposes screening and behavioral circadian measures as adjuncts to care, while calling for stronger trials to establish who benefits and whether these approaches improve core ADHD symptoms.
A perspective article published December 10, 2025, in Frontiers in Psychiatry argues that delayed circadian timing is a common and clinically relevant feature for a substantial subgroup of people with ADHD, and proposes adding sleep and circadian assessment to care. The authors point to evidence of later sleep-wake schedules and delayed biological rhythms, but stress that ADHD is not a circadian disorder in every person and that more rigorous trials are needed before chronotherapy can be treated as an established ADHD treatment.
The article reports that sleep difficulties are frequent in ADHD: insomnia or other sleep disturbances affect up to 80% of adults and 82% of children in the cited research. It estimates that delayed sleep-wake timing occurs in roughly 73% to 78% of people with ADHD. These are upper estimates from the studies reviewed, not rates that apply to every individual or a new population survey conducted by the authors.
Biological measures reviewed in the paper also point to later timing. Dim-light melatonin onset, a marker used to estimate circadian phase, is reported to be delayed by about 45 minutes in children and 90 minutes in adults with ADHD compared with reference groups. The authors also describe findings involving blunted or delayed cortisol rhythms, smaller pineal gland volume in some studies, and altered rhythms in peripheral clock genes. The perspective synthesizes earlier studies; it does not report a new clinical trial.
The authors review intervention research in which melatonin and bright-light therapy advanced circadian phase in ADHD groups. Some studies link phase advances with symptom improvement, and sleep programs have improved sleep quality, functioning, and ADHD symptoms in children. The authors propose screening for sleep problems, characterizing chronotype and sleep timing, and testing routines such as fixed wake times, morning light exposure and reduced evening light. They suggest selective low-dose melatonin when a delayed phase is suspected or established, rather than as a universal recommendation.
Adding Circadian Timing to ADHD Care
The perspective could broaden how clinicians and families think about persistent sleep difficulties alongside ADHD. If a person’s internal clock is substantially delayed, difficulty waking or sleeping at conventional times may compound daytime impairment. Identifying that pattern could help tailor practical support, rather than treating every sleep complaint as the same problem.
However, the proposed approach is an adjunct to ADHD care, not a replacement for established assessment or treatment. The evidence reviewed suggests circadian interventions may help some people, but it does not establish that they work for all ADHD patients or that shifting circadian phase reliably changes core symptoms. The practical implication is to take sleep timing seriously while maintaining appropriate expectations and seeking clinical guidance, especially before using melatonin.
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Evidence Behind the Circadian Link
ADHD is a neurodevelopmental condition associated with inattention, hyperactivity and impulsivity. Research has increasingly examined sleep and circadian patterns as part of the wider clinical picture. The 2025 paper is a Perspective article: it brings together prior findings and makes a case for a clinical pathway, rather than presenting a systematic review with a new pooled analysis or original patient data.
The authors describe the relationship as potentially bidirectional and complex. Circadian delay may interact with ADHD symptoms, but the reviewed associations do not by themselves show that circadian disruption causes ADHD. Sleep problems can also have multiple contributors. The article notes that some studies found sleep-related differences even after accounting for anxiety and depression, but this does not rule out other influences in individual cases.
Chronotherapy refers here to interventions intended to shift or better align circadian timing. The suggested behavioral measures include consistent wake times, morning bright light, less light and screen exposure in the evening, and regular daily routines. The authors also discuss exercise and combined approaches, while noting that some evidence for these strategies comes from people without ADHD and needs direct testing in ADHD populations.
“Circadian rhythm dysfunction is a clinically significant and highly prevalent phenotype in a substantial subgroup of individuals with ADHD.”
— The authors of the Frontiers in Psychiatry perspective
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Who Benefits From Clock Shifts
The paper does not establish how many people with ADHD have a clinically meaningful circadian delay, which assessment method should guide treatment, or which intervention works best for specific patients. The reported percentages and timing differences come from studies with differing methods and populations; they should not be read as precise predictions for an individual.
It also remains unclear whether advancing circadian phase directly improves core ADHD symptoms, or whether reported gains reflect better sleep, other treatment effects, or a combination. The perspective calls for larger, well-designed trials that stratify participants by circadian profile. The article does not recommend stopping or changing prescribed ADHD medication. Melatonin timing and dose can matter, so people considering it should consult a health professional.
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Trials Must Test Patient Subgroups
The next step identified by the authors is rigorous clinical research comparing circadian-focused protocols and measuring both sleep outcomes and core ADHD symptoms. Trials will need to clarify how to identify likely responders, whether behavioral measures alone are sufficient, and when melatonin or bright light adds benefit. Until those results are available, the proposed screening and behavioral pathway remains a clinical proposal supported by emerging evidence, not a settled standard of care.
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Key Questions
Does this article say ADHD is a circadian rhythm disorder?
No. The perspective argues that circadian disruption is common in a substantial subgroup of people with ADHD. It does not claim that everyone with ADHD has a circadian disorder or that circadian delay causes ADHD.
What circadian differences does the article describe?
It reviews evidence of later sleep-wake timing and delayed dim-light melatonin onset—about 45 minutes in children and 90 minutes in adults in the cited research—alongside findings on cortisol and other biological rhythms.
Are light therapy and melatonin proven ADHD treatments?
The perspective reports that studies have advanced circadian phase with bright light and melatonin, with some evidence linking phase shifts to symptom improvement. It calls for stronger trials, so these approaches are not established as effective for every person with ADHD.
What behavioral steps do the authors propose?
They suggest assessing sleep timing and chronotype, keeping a consistent wake time, getting light in the morning, limiting evening light and screen exposure, and regularizing daily routines. These measures are proposed as adjuncts to care, not substitutes for professional ADHD treatment.
Source: hn
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