When it might be a sleep disorder

Sometimes it’s more than a late clock

A lot of what makes sleep hard for neurodivergent people is timing and wiring. But sometimes there’s a specific, nameable sleep disorder underneath – and those are worth knowing about, because they can be assessed and helped.

They’re more common alongside ADHD and autism than in the general population – restless legs syndrome, for instance, affects roughly a third to over 40% of adults and children with ADHD, against roughly one in ten (or fewer) in the general population, and insomnia and sleep problems run markedly higher in both ADHD and autism too (sleep disorders in ADHD and autism, BJPsych Advances; literature review, PMC). Naming them matters for two reasons: some need medical attention in their own right, and some can look so much like ADHD that they get mistaken for it.

The ones worth knowing about

Delayed sleep phase

A body clock set hours later than the world runs on – the clinical name for the late-night, late-morning pattern so common in ADHD. If your sleep happens later than you’d like and that causes real problems – trouble getting up for work, or feeling unwell from too little sleep – delayed sleep phase may be part of it. A late sleep window on its own can be a normal body-clock pattern.

Insomnia

Trouble falling asleep or staying asleep, night after night, even when you have the time and the chance for it. Often it rides on top of a busy mind or a late clock.

Restless legs, and restless nights

An uncomfortable urge to move your legs in the evening, or a lot of movement once you’re asleep – both of which break up the night. These are more common in ADHD and autism, and they have a physical link worth chasing (see below).

Sleep apnoea

Breathing that stops and starts through the night, often with loud snoring or gasping, leaving you unrefreshed however long you were in bed. It’s important to have it checked by a medical professional, because it affects your health well beyond sleep.

Sleeping too much, such as narcolepsy or hypersomnia

Not everyone’s problem is too little sleep. Some people sleep long and heavily and still wake exhausted, or feel dragged down by sleepiness in the day. That’s worth taking seriously too.

Insomnia that won’t shift

Most people have runs of poor sleep. When it goes on for three months or more, on at least three nights a week, and it’s affecting your days, it’s called chronic insomnia, and it deserves attention in its own right.

The recommended first step in the UK is CBT for insomnia, or CBT-I. It works on the habits and timings that keep insomnia going, and on the worries about sleep that build up at night. Your GP can tell you what’s available locally, and in England you can refer yourself to NHS Talking Therapies, where some services offer it. NICE also recommends Sleepio, a digital CBT-I programme, which your GP may be able to offer.

CBT-I often needs adapting for ADHD and Autistic people, and one part of it, sleep restriction, isn’t safe for everyone, so it’s best done with support. Heather Darwall-Smith, who founded the ADHD Sleep Club, is trained in CBT-I and integrates it into her therapy work.

If you sleep well once you’re asleep and the trouble is that it all happens late, see the section on delayed sleep phase above. The approaches for a late body clock are different.

When sleep problems look like ADHD

Here’s the part that gets missed. Some sleep disorders produce exactly the things ADHD is known for – trouble concentrating, restlessness, irritability, a foggy and forgetful day. Untreated sleep apnoea can look so like ADHD that people are sometimes diagnosed with one when they have the other – a documented case describes a teenager whose longstanding ADHD diagnosis was retracted once undiagnosed sleep apnoea was found and treated (obstructive sleep apnoea mimicking ADHD, case report). And where someone genuinely has both, the sleep disorder makes the ADHD harder to live with.

None of this is a reason to doubt an ADHD diagnosis. It’s a reason to make sure a sleep disorder sitting alongside it, or underneath it, isn’t being missed – because that’s a physical thing, and physical help is available.

The iron connection

One that’s easy to overlook: low iron. Iron matters for the brain chemistry behind restful sleep, and low iron stores are linked to restless legs and broken nights, particularly in ADHD and autism – a review found that found iron deficiency in over a third of adults with ADHD, and in Autistic children with insomnia, those with restless legs syndrome had markedly lower iron stores than those without (iron deficiency and RLS in ADHD, PubMed; iron deficiency and RLS in autism, PMC). It’s a simple thing to check – a ferritin blood test through your GP – and worth checking. The study counted iron as low when ferritin was below 50, which is higher than many standard lab cut-offs, so a result your GP calls normal may still be low for restless legs. Ask about your ferritin level specifically, and don’t start iron supplements without a blood test – too much iron is harmful.

What to do about it

If any of this sounds like you, the move is the same: take it to your GP and ask specifically about a sleep assessment or referral. Bring the names – it helps the conversation. Loud snoring or gasping, strong urges to move your legs, acting out your dreams, or daytime sleepiness that rest doesn’t touch are all worth flagging. These have causes that can be assessed and managed, and the club works alongside that, not in place of it.

If you’re very sleepy during the day, don’t drive until you’ve spoken to your GP. This matters especially if you think you might have sleep apnoea.

Talk to your GP if you notice:

Your sleep changes after starting or changing ADHD medication. Talk to whoever prescribes it before changing anything yourself.
An urge to move your legs in the evening, often with creepy-crawly feelings, that eases when you move. This may be restless legs. Ask your GP to check your ferritin (iron stores) specifically.