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A December 2025 perspective in Frontiers in Psychiatry argues that delayed circadian timing is a common, clinically relevant feature for a substantial subgroup of people with ADHD, though not everyone with the condition. It reviews evidence that some interventions can shift circadian timing and proposes behavioral strategies as adjuncts, while calling for larger, well-designed trials to establish effects on 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 subgroup of people with ADHD, and proposes testing sleep and clock-focused care alongside established treatment. The authors draw on prior research linking ADHD with evening chronotype and later biological rhythms; their article is a synthesis and clinical proposal, not a new clinical trial or a change to treatment guidelines.
The authors report that sleep problems are common in ADHD, citing estimates of insomnia or sleep disturbances in up to 80% of adults and 82% of children. They also cite delayed sleep-wake timing in as many as 78% of people with ADHD. These are estimates from studies summarized in the perspective, not results from a new study conducted by its authors. The article stresses that circadian disruption occurs in a substantial subgroup, not all people with ADHD, and may interact with symptoms in both directions.
The review describes biological findings that support an association: dim-light melatonin onset, a marker of circadian phase, is reported as delayed by about 45 minutes in children and 90 minutes in adults with ADHD. It also discusses research reporting altered cortisol rhythms, differences in pineal gland volume, and attenuated rhythms in peripheral clock-gene markers such as BMAL1 and PER2. The authors present these findings as converging evidence, while noting that they do not by themselves establish that circadian delay causes ADHD.
The article says intervention studies have shifted circadian phase in ADHD populations using melatonin and bright light. It describes emerging associations between earlier phase timing and symptom improvement, and reports that sleep programs have improved sleep and functioning, as well as ADHD symptoms, in children. The authors propose screening for sleep and circadian difficulties, assessing chronotype and sleep patterns, and using fixed wake times, morning light, reduced evening light and regular schedules as possible adjuncts. They suggest selective low-dose melatonin when a delay is confirmed or likely; this is a proposal in the perspective, not individualized medical advice.
How Body-Clock Care Could Fit ADHD Treatment
The perspective could encourage clinicians and patients to treat sleep timing as a relevant part of ADHD care rather than assuming every sleep difficulty is incidental. For people whose internal timing is delayed, regularizing wake times and light exposure may be practical approaches to investigate alongside usual care. The article frames such strategies as adjuncts, not replacements for established ADHD treatment.
The distinction matters because the evidence has not yet shown that circadian interventions reliably improve core ADHD symptoms across the broader population. If future trials identify who benefits, care could become more tailored; if not, the apparent link may reflect a feature of some patients without being a useful treatment target for others. The authors call for stratified trials to measure symptom outcomes, identify likely responders and determine effective protocols.
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Evidence Behind the Circadian Link
The Frontiers article is labeled a Perspective and synthesizes earlier research rather than reporting a single new experiment. Its case rests on several types of evidence: reports of evening chronotype and later sleep schedules, objective measures such as melatonin timing and actigraphy, and studies of other biological rhythms. The authors also describe sleep difficulties that remain associated with ADHD in research accounting for anxiety and depression, while recognizing that sleep and ADHD symptoms can influence one another.
Some cited work suggests ADHD medication may interact with circadian biology. The perspective notes studies in children in which methylphenidate was associated with improved daytime melatonin suppression and an earlier melatonin rhythm. That observation does not establish a general medication effect or show that medication should be changed to alter sleep timing. The article instead argues for further research into how circadian patterns, treatments and symptoms relate.
“circadian rhythm disruption represents a highly prevalent and clinically important phenotype”
— Authors of the Frontiers in Psychiatry perspective
What the Evidence Cannot Yet Establish
The perspective does not establish that circadian disruption causes ADHD, nor that changing circadian timing will improve symptoms for most people with ADHD. The underlying findings come from different studies and measures, and the reported prevalence and timing estimates are not results from one standardized population study. It is also unclear which clinical or biological features best identify people likely to benefit from a clock-focused approach.
The authors call for well-designed trials to test core ADHD outcomes, define responder groups and optimize intervention protocols. The article does not provide a new treatment guideline, a single recommended melatonin dose for individual patients, or evidence that light and behavioral approaches can replace medication or other established care. Safety, timing and suitability of interventions depend on the person and should be discussed with a qualified clinician.
Trials Must Test Who Benefits
The next research step described by the authors is stratified clinical trials that assess participants’ chronotype and circadian phase, then track changes in ADHD symptoms as well as sleep and daily functioning. Such studies could clarify whether phase advancement itself is linked to improvement, which intervention combinations work, and which groups are most likely to respond. Until that evidence is available, the proposal remains a research-informed adjunctive approach rather than a settled standard of care.
Key Questions
Does the article say ADHD is a circadian rhythm disorder?
No. It argues that circadian disruption is a common, clinically relevant feature in a subgroup of people with ADHD. It does not say that every person with ADHD has a circadian disorder or that circadian disruption causes ADHD.
What circadian differences does the perspective describe?
It summarizes research reporting evening chronotype and later sleep-wake timing, along with dim-light melatonin onset delayed by about 45 minutes in children and 90 minutes in adults with ADHD. It also discusses altered cortisol rhythms and other biological markers.
Can light or melatonin treat ADHD?
The article reports studies in which bright light and melatonin shifted circadian phase, and describes emerging links between phase advancement and symptom improvement. It does not establish these as stand-alone ADHD treatments or recommend that readers start melatonin without clinical guidance.
What does the article recommend clinicians consider?
The authors propose screening for sleep and circadian problems and considering chronotype, sleep tracking and, when feasible, dim-light melatonin onset. They suggest behavioral measures such as consistent wake times and morning light as possible adjuncts, with treatment decisions made with a clinician.
Source: hn
