The Clock in Your Cells: What a New UCLA Trial of Nearly 100 Older Adults Reveals About Insomnia Therapy and How Fast You Age

A Singular Point of View

If you have ever lain awake at half past two, doing the maths on how many hours of sleep are technically still possible before the alarm, this is for you.

Somewhere in your bloodstream, right now, a clock is running slightly too fast or slightly too slow — and until recently, nobody could tell you which, or why. It is kept not in hours and minutes but in DNA methylation: tiny chemical tags that attach to your genes over a lifetime, switching some on and some off, leaving behind a kind of running commentary on how hard your body has been working to keep up. Scientists can now read that commentary and translate it into a single number: your pace of biological ageing, ticking faster or slower than your birth certificate would suggest. A new study from UCLA Health, published in The Lancet Healthy Longevity this August, found that treating insomnia with a structured talking therapy slowed that number down. Not the candles on your next birthday cake. The rate at which your cells are, quite literally, wearing out.

Perhaps you are the one doing that arithmetic at half past two. Perhaps you are the son or daughter two rooms away, hearing your mother’s landing light click on for the third time tonight, and wondering whether her sleeplessness is something to fix or simply something to fear. Perhaps a GP used the phrase “clinical insomnia” about you for the first time only last month, and you are still deciding how seriously to take it. Wherever you are standing, this study has something to say directly to you: the poor sleep you have been treating as background noise may be doing more than making tomorrow harder. It may be setting the pace at which the rest of you ages.

What the researchers actually did

Dr Judith Carroll and her colleagues at UCLA recruited nearly 100 older adults, every one of them living with clinically diagnosed insomnia — sleeplessness that does not resolve on its own and has gone on long enough to have a name. Half received cognitive behavioural therapy for insomnia, usually shortened to CBT-I: a structured, multi-session therapy delivered by a trained clinician that targets the specific thoughts and habits keeping the insomnia alive, rather than simply managing the tiredness that follows it. The other half received sleep education therapy instead — sound, general information about good sleep habits, but without the behavioural retraining. Before an eight-week treatment period began, everyone had blood drawn; more blood was drawn at follow-up visits stretching across the two years afterwards. From that blood, the researchers extracted DNA and read it through three separate epigenetic clocks — DunedinPACE, GrimAge and PC-PhenoAge, three different mathematical formulas for estimating how quickly a body is ageing at the cellular level.

If you had been one of the participants given CBT-I, here is roughly what would have happened to you. You would have been nearly three times more likely to see your insomnia go into remission than if you had received sleep education alone. And on the DunedinPACE measure specifically, your pace of biological ageing would have slowed significantly more than it did for the sleep education group. The other two clocks, GrimAge and PC-PhenoAge, did not show that same significant slowing — worth knowing before this becomes bigger, in your mind, than it currently is.

Does that land differently once you picture it happening to your own body, tonight, rather than to “older adults” in a trial somewhere in Los Angeles? This is not a statistic about somebody else’s cells. It is about what happens in yours at half past eleven on a bad night — the phone glowing on the pillow beside you, a conversation from three days ago replaying uninvited, the small silent arithmetic of how many hours are left before the alarm.

Why this matters beyond insomnia

Between 10 and 25 per cent of adults over 65 in the United States live with clinical insomnia, and earlier research had already linked poor sleep to faster biological ageing and a higher risk of heart disease, diabetes and earlier death. What makes Carroll’s study different is that it moves past simply noticing a pattern. It did not just observe that poor sleepers age faster; it treated the insomnia directly, then measured whether the ageing process itself responded — and it did. As Carroll put it, insomnia in older adults has traditionally been “treated as a quality-of-life issue,” when the evidence now suggests it belongs alongside diet and exercise as something you can actually change that changes how your body ages.

If ADHD already lives in your house

If you have ADHD, or you are raising or living alongside someone who does, this next part is worth your attention, with one flag attached before we go further: this study did not test any of it. Chronic sleep disruption turns up constantly in ADHD, at every age, from a child who cannot switch their mind off at bedtime to an adult whose thoughts arrive fastest at precisely the moment the house goes quiet. Executive function — the mental machinery behind planning, patience and emotional regulation — is already known to run poorly on too little sleep, in ways that can look, to you, exhausted, at eleven at night, indistinguishable from the ADHD itself getting worse. Nobody has yet run this trial in people with ADHD. That bridge is this piece’s own extension beyond what the study tested, not the researchers’ finding, and it deserves to be treated as plausible rather than proven.

What this study cannot promise you

Here is what this finding cannot yet do for you. It was run at a single site in Los Angeles, with fewer than 100 participants, so it needs to be repeated in a larger, more diverse sample before you treat it as settled for people who do not resemble this trial’s participants. The researchers themselves do not yet know whether the effect differs between men and women, or whether other treatments for insomnia — sleep medication, or structured practices like Tai Chi — might slow the biological clock in a similar way. And of the three ageing measures used, only DunedinPACE moved significantly; the other two did not follow suit to the same degree.

Let me slow down here, because hope without honesty helps no one. This is one careful study. It is not a verdict on your future. None of that cancels the finding out — it simply means the honest version of this story is “a promising early result,” not “sleep therapy reverses ageing,” and you deserve the honest version, not the headline one.

What you can do about it tonight

You do not need to wait for a larger trial to start treating your sleep with the same seriousness as your diet. CBT-I is a recognised, evidence-based treatment. In the UK it is available through the NHS in some areas, and through accredited private practitioners and reputable digital programmes elsewhere; you do not need to have reached retirement age to benefit from it.

• Ask your GP for CBT-I by name, rather than a general referral for “sleep problems.” It is a distinct, structured therapy, not the same as being handed a leaflet on sleep hygiene.
• Keep the same waking time every day, weekends included. Irregular timing is one of the specific habits CBT-I is designed to unpick.
• If you are still awake after roughly twenty minutes, get up. Go to another room, do something calm and dimly lit, and return to bed only once you feel sleepy.
• If ADHD is part of your life or your household, raise sleep disruption with a clinician in its own right, rather than assuming it is simply “part of the ADHD” and therefore untouchable.
• Use the bed for sleep only, not for scrolling, working or worrying, so your body relearns what that room, at that hour, is actually for.

None of this replaces a full course of CBT-I delivered by someone trained in it. But it is somewhere to start while you wait for that referral, and it rests on the same behavioural principles the UCLA trial used.

Not a promise, but a reason to try

You cannot control how fast your cells divide, and lying awake doing mental arithmetic about your own DunedinPACE score would rather defeat the point. But you can control whether tonight’s sleep gets treated as optional or as something closer to medicine. This study offers something rarer than a miracle cure: evidence that an ordinary, learnable set of habits, taught over a handful of structured sessions, may already be working quietly on your behalf, at a level you will never see or feel, one night at a time. That is worth getting into bed for, on time, tonight.

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Source: Carroll, J. et al., “Cognitive behavioural therapy for insomnia and epigenetic ageing: secondary analysis from a randomised controlled trial,” The Lancet Healthy Longevity, 12 August 2026 (DOI: 10.1016/j.lanhl.2026.100861); UCLA Health news release, 8 September 2026.