You are not lazy. You are two hours off schedule.
It is twenty to midnight, and you are lying in the dark doing the thing you swore you would not do again tonight: running the next day backwards through your head, wide awake, while the rest of the house has been asleep for hours. Your body is behaving as though it is still mid-afternoon somewhere. In a sense, it is. You are not lying there because you are undisciplined, or because you left your phone on too long, or because you simply will not commit to a bedtime like everyone else seems to manage without trying. You are lying there because, for reasons only decoded in the last few years, your internal clock may be running on a different schedule to the one printed on your alarm clock. This is not a discipline problem. It is a timing problem — and new research is finally showing, in hard numbers, just how far apart the two clocks can drift.
If you have ADHD (attention-deficit/hyperactivity disorder, the neurodevelopmental condition involving persistent difficulties with attention, impulse control and, as this piece explores, timing itself), or you are raising a child who does, this will not be news to you in feeling. What is new is the evidence. A landmark clinical trial out of the Netherlands, alongside a fresh wave of 2025 research reviews, has now measured exactly how badly the ADHD body clock lags behind everyone else’s — and, more usefully, what happens when researchers try to nudge it back into line. Some of what they found may put a shape to something you have been fighting for years without a name for it. Some of it, in the interest of being straight with you, will complicate the tidy story you might have been hoping for.
The two-hour lag nobody warned you about
Deep inside your brain sits a cluster of cells called the suprachiasmatic nucleus, which acts as your body’s master clock. Its main way of telling the rest of you what time it is comes down to a hormone called melatonin, released each evening as darkness falls. Researchers measure the moment this release begins in dim light — unsurprisingly called dim-light melatonin onset, or DLMO — because it is one of the most reliable biological markers of when your body genuinely believes night has begun, regardless of what the clock on your wall says.
For years, the Dutch psychiatrist Professor J. J. Sandra Kooij and her colleagues at the PsyQ adult ADHD clinic in The Hague have been building a body of evidence that, in adults with ADHD, that internal night arrives late. Across their studies and the wider research they have now gathered together, dim-light melatonin onset occurs roughly 90 minutes later in adults with ADHD than in adults without it, and around 45 minutes later in children with the condition. Between 73 and 78 per cent of people with ADHD show this kind of delayed sleep-wake pattern — not the odd bad night, but a structural, measurable lag built into the way their bodies keep time. Cortisol, the hormone that should be helping haul you out of bed in the morning, follows the same pattern: lower and later than it should be, particularly in that crucial first hour after waking, which may explain why dragging yourself out of bed can feel like wading through wet sand even after what should have been enough sleep.
Put plainly: if you have ever been told to simply go to bed earlier, and found that your body flatly refused to cooperate no matter how much you wanted it to, this is very possibly why. You were not failing at a simple instruction. You were fighting a biological clock running roughly two hours behind the one everyone else was using.
What the newest trial actually did
Knowing that the clock runs late is one thing. Knowing whether you can safely reset it is another question entirely, and it is the one a team led by researcher Emma van Andel, working with Denise Bijlenga, Suzan Vogel, Aartjan Beekman and Professor Kooij, set out to answer in a trial published through Amsterdam UMC and the Journal of Biological Rhythms. If you are the kind of reader who wants to see the actual mechanics before trusting the conclusion — and you are entitled to — here is exactly what they did.
They recruited 49 adults aged 18 to 55, all diagnosed with both ADHD and delayed sleep phase syndrome (a recognised sleep disorder in which a person’s natural sleep and wake times are shifted markedly later than is workable for their daily life — the exact difficulty this trial was designed to treat). Forty-six completed the study. Everyone first received a single session of sleep-hygiene education, because good research controls for the obvious explanations before testing the interesting ones. Then, over three weeks, participants were split at random into three groups: a low dose of melatonin (0.5mg) timed three to five hours before each person’s own measured DLMO and gradually shifted earlier each week; an identical-looking placebo; or that same melatonin dose combined with thirty minutes of bright light exposure (10,000 lux, roughly twenty times brighter than typical indoor lighting) every morning between 7 and 8am. Sleep was tracked objectively with wrist actigraphy — a motion-sensing device worn like a watch — as well as through daily sleep diaries, with a follow-up check two weeks after the intervention ended.
What actually shifted, and what stubbornly did not
Here is where the story earns its complexity. The melatonin-only group saw their DLMO move 1.5 hours earlier. The melatonin-plus-light group moved further still: a full two-hour advance in their body clock, confirmed by the actigraphy data, not just by how participants felt. On paper, that is a striking result — a body clock nudged back by two hours in three weeks, using nothing more exotic than a low-dose supplement and a bright lamp at breakfast.
Does it surprise you, though, that shifting the internal clock did not automatically mean people actually fell asleep two hours earlier? It certainly complicated matters for the research team. Actual sleep onset times lagged behind the biological shift in both active groups; the melatonin-only participants drifted to sleep roughly 59 minutes earlier than the placebo group by the end of treatment, a meaningful difference but not a statistically decisive one, and even the group with the full two-hour DLMO advance did not see their bedtime move by nearly that much. The body’s internal night had arrived earlier. The habit of staying up, scrolling, working, or simply resisting sleep because that is what has always happened at that hour, had not caught up with it.
The ADHD symptom results told an equally unvarnished story. In the melatonin-only group, average scores on a standard ADHD rating scale fell from 33 to 27 — a 14 per cent reduction, real and clinically noticeable, though nowhere near symptom remission. The melatonin-plus-light group, despite achieving the larger clock shift, did not show a matching improvement in ADHD symptoms overall, although both active groups reported some improvement in inattention specifically. If you came to this expecting a straightforward story where fixing the clock fixes the ADHD, the researchers’ own conclusion is worth sitting with: chronotherapy — treatment that works by deliberately timing light and melatonin to shift your body clock, rather than by targeting ADHD symptoms directly — moved the biology, but genuinely shifting sleep timing and behaviour required what they called “extensive behavioural coaching” alongside it. The clock is not the whole picture. It is a significant, previously underestimated piece of it.
You might be reading this at your kitchen table with a letter from your child’s school still unopened beside you, wondering whether the meltdowns before assembly every morning have anything to do with a body clock that simply has not caught up with the school bell yet. Or you might be the adult who was only diagnosed with ADHD in the last year or two, finally making sense of a lifetime of being called lazy for something that, it turns out, has a measurable biological signature. Either way, this research was built with people very like you in mind.
Why this reaches further than one Dutch clinic
This is not a niche finding sitting quietly in one European research group. A 2025 review drawing together the wider evidence base restates the same pattern across multiple studies and describes ADHD, at least in a meaningful subset of cases, as functioning like a circadian rhythm disorder in its own right — not merely a condition that happens to disrupt sleep as a side effect. That reframing matters, because it changes the question from “why can’t you just go to sleep” to “what would it take to help a genuinely delayed body clock catch up with the day it has to live.”
Closer to home, a 2025 modified Delphi consensus — a structured process in which a panel of specialists work towards agreement on best practice — looked specifically at how the UK’s health system should manage delayed sleep onset in adults with ADHD. Its clearest practical recommendation was that melatonin, for newly diagnosed patients, could reasonably be started in primary care and monitored by GPs, rather than requiring a lengthy wait for a specialist sleep clinic that, in much of the country, simply does not have the capacity to see everyone who needs it. If you have ever sat on an NHS waiting list wondering whether anyone was going to take your exhaustion seriously, that is a meaningful shift in how seriously the system is beginning to take this particular piece of the ADHD picture.
What you can actually try this week
None of this is a substitute for a conversation with your GP, particularly around melatonin dosing and timing, which needs to be tailored to your own DLMO rather than guessed at. But there is a genuine, evidence-backed starting point you can put in place tonight, drawn directly from what worked, and did not, in the trial above.
- Anchor your wake time, not your bedtime. The trial’s protocol worked by shifting morning light and evening melatonin together; a fixed wake time, seven days a week, gives your body clock a stable point to reset around, even on the mornings you would rather not.
- Get outside, or under a bright light, within the first hour of waking. The bright light used in the trial was roughly 10,000 lux; UK daylight on an overcast morning is still typically brighter than most indoor rooms, so even ten to fifteen minutes outdoors shortly after waking mimics the light-therapy arm of the study.
- Dim your evenings deliberately, starting earlier than feels necessary. Because DLMO in ADHD arrives roughly 90 minutes later than average, waiting until you feel sleepy before dimming lights and screens is usually waiting too long.
- If you and your GP discuss melatonin, ask about timing before dose. The trial’s meaningful shift came from a small 0.5mg dose taken hours before natural melatonin onset, not from a larger dose taken right at bedtime, which is how melatonin is most commonly, and less effectively, used.
- Expect the habit to lag behind the biology. The trial’s clearest lesson was that a shifted body clock does not instantly produce a shifted bedtime. Pair any light or melatonin changes with a genuine wind-down routine, or the two-hour biological shift you are aiming for may simply go unused.
What this trial cannot promise you
Here I want to slow down. Hope without honesty helps no one, and a piece like this can do you real harm if it sends you into an appointment expecting more certainty than the evidence actually offers.
So before you take any of this to your GP, here is what to hold lightly. This was a small trial: 49 adults, drawn from one clinic population in the Netherlands, not a nationally representative sample, and not conducted in children at all — so if you are the parent asking about your child’s mornings rather than your own, treat everything above as a strong clue, not a verdict. The bright light arm produced the largest clock shift but, puzzlingly, not the largest improvement in symptoms, which should stop you assuming that moving the clock further always means feeling better faster. Melatonin bought over the counter in the UK is regulated differently from the prescription version used in this trial, and a dose timed precisely against your own measured DLMO is not the same as guessing with a bottle from the pharmacy shelf. And even in the best-responding group, symptoms fell by 14 per cent. That is real. It is not a cure. If anyone tells you that fixing your sleep will fix your ADHD, they are promising you more than this research, or any research so far, can honestly deliver.
Where this leaves you tonight
You did not choose a body clock that runs two hours behind the day you are expected to live. But you are not without options inside that gap, and for the first time, researchers can tell you with some precision where to spend your effort: the first hour after you wake, the hour before you mean to sleep, and a conversation with your GP that no longer has to start from nothing. Try shifting your mornings before you try to force your evenings. Give it two weeks before judging whether it is working, in line with how the trial itself measured change. And when you do finally feel your eyes grow heavy at a reasonable hour, notice it — because for a body that has spent years running on its own time zone, that alone is worth paying attention to.
Source: van Andel, E., Bijlenga, D., Vogel, S. W. N., Beekman, A. T. F., & Kooij, J. J. S. (2022). “Effects of Chronotherapy on Circadian Rhythm and ADHD Symptoms in Adults with Attention-Deficit/Hyperactivity Disorder and Delayed Sleep Phase Syndrome: A Randomized Clinical Trial,” Journal of Biological Rhythms / Chronobiology International, Amsterdam UMC. Additional context: “ADHD as a circadian rhythm disorder: evidence and implications for chronotherapy,” Frontiers in Psychiatry, 2025; and “The optimal system of care for the management of delayed sleep onset in adult ADHD in the UK: a modified Delphi consensus,” Frontiers in Psychiatry, 2025.
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