4-min read
If you can't fall asleep with ADHD even when you're wiped out, one study in adults points to a possible reason: your body's internal night-timer may run late. In adults who had ADHD and sleep-onset insomnia, the nightly melatonin signal started 83 minutes later than in people without ADHD (Van Veen, 2010). That is a clue, not an answer.
Why can't I fall asleep with ADHD when I'm this tired?
One study looked directly at this in adults. Van Veen (2010) studied 40 adults with ADHD, aged 18 to 55, and compared them with healthy adults of similar age. Of those 40, 31 reported sleep-onset insomnia, meaning they struggled to fall asleep, and 9 did not.
The researchers tracked a hormone called melatonin, which rises in the evening as the body prepares for sleep. In the adults with ADHD, that evening melatonin rise started 83 minutes later than in the healthy comparison group. This lateness was driven by the group with sleep-onset insomnia. Within the ADHD sample, the melatonin rise came 75 minutes later in the insomnia group than in the group without it (p = .02).
Their sleep clock looked shifted too. The adults with ADHD and sleep-onset insomnia started their sleep period 53 minutes later and woke 60 minutes later than the healthy group. The strength of their daily rhythm, its amplitude, was 10.8 plus or minus 11.7 percent lower.
Here is the honest limit. This was an observational study, so it can show that a late body clock and trouble falling asleep tend to appear together, but it cannot prove one causes the other. The authors say plainly that they cannot conclude whether the shifted melatonin signal is a cause of the delayed sleep or a consequence of it. The comparison group without insomnia was small, just 9 people. So this is a real pattern in adults, but not a settled explanation.
What about the link between delayed sleep and ADHD symptoms?
You might wonder whether a late sleep clock and ADHD traits travel together more broadly. One large study suggests they do, though it was done in teenagers, not adults, so read it as background rather than as a finding about you.
Sivertsen (2014) surveyed 9,338 Norwegian adolescents aged 16 to 19. About 3.3 percent were classified as having delayed sleep phase, meaning their natural sleep timing ran late. Those adolescents reported more ADHD symptoms than their peers. The gap was largest for inattention, a moderate difference (d = 0.71), and smaller for hyperactivity and impulsivity (d = 0.47). In the fully adjusted analysis, adolescents high in inattention had about twice the odds of delayed sleep phase (odds ratio 2.11).
Notice what this can and can't say. It was cross-sectional, a single snapshot in time, so it cannot tell you whether late sleep worsens attention, whether attention problems push sleep later, or whether something else drives both. Delayed sleep phase here was based only on self-report, with no clinical exam, no sleep diary and no device tracking. The response rate was 53 percent. So this study describes a link in adolescents. It does not measure adults, and it does not establish cause. Still, it lines up with the adult melatonin pattern above, which is worth holding loosely in mind rather than treating as proof.
Does the research say what to do about it?
Not yet, and it is worth being straight about that. The one intervention study here was small, uncontrolled, and done in teenagers rather than adults.
Becker (2021) ran a pilot trial of a six-session behavioral sleep program in 14 adolescents aged 13 to 17 who had ADHD and sleep problems. Their sleep-quality scores improved by a large amount from before to after (g = 1.74), and the share rated as poor sleepers fell from 71.4 percent to 21.4 percent right after the program. Parent-rated inattention improved too (g = 0.83).
Those numbers look encouraging, but the study was built to test whether the approach was doable, not whether it works. There were just 14 people and no control group, so there was nobody to compare against and no way to rule out that people improve on their own or simply from being in a study. The authors themselves say a randomized controlled trial is needed to test whether it actually helps. And again, these were adolescents.
So across these three studies, here is where things stand for an adult who can't fall asleep with ADHD. There is a measured pattern of a late-running body clock, and a broader association between late sleep and attention symptoms. There is not yet evidence that supports a specific fix for you. That gap is real, and no one should paper over it.
Try this today: for one week, write down the clock time each night when you first feel a genuine wave of sleepiness, not when you get into bed, and the time you actually fall asleep, so you have your own record of when your body's night signal seems to arrive.
Sources
- Van Veen M, Kooij J, Boonstra A, et al.. Delayed Circadian Rhythm in Adults with Attention-Deficit/Hyperactivity Disorder and Chronic Sleep-Onset Insomnia. Biological Psychiatry (2010). doi:10.1016/j.biopsych.2009.12.032
- Sivertsen B, Harvey A, Pallesen S, et al.. Mental health problems in adolescents with delayed sleep phase: results from a large population‐based study in N orway. Journal of Sleep Research (2014). doi:10.1111/jsr.12254
- Becker S, Duraccio K, Sidol C, et al.. Impact of a Behavioral Sleep Intervention in Adolescents With ADHD: Feasibility, Acceptability, and Preliminary Effectiveness From a Pilot Open Trial. Journal of Attention Disorders (2021). doi:10.1177/10870547211056965
[!note] Founder review required before publishing. Every claim above descends from a digest approved in KB Tab 3.