Teenagers and phones: late-night scrolling costs sleep, but the phone isn’t the whole story

The short version

• Late-night phone use costs sleep. In a new study of 425 teenagers, nights with more phone use after 10pm went with falling asleep about an hour later and getting about 20 minutes less sleep.
• It works both ways. Teenagers who aren’t sleepy reach for their phones, so the phone isn’t always the cause.
• Short sleep affects everyone. Lost sleep blunts focus, memory, mood and impulse control in anyone, teenager or adult, and can look a lot like ADHD.
• ADHD raises the stakes. Many young people with ADHD use their phone to calm or stimulate themselves. Poor sleep then makes ADHD symptoms worse, which drives more phone use.
• Ask, don’t tell. Rejection sensitivity is common in ADHD, so instructions can feel like criticism. Help your teenager design their own plan.
• What helps. Charge the phone outside the bedroom, aim for phones down by 10pm on school nights, leave a wind-down gap and keep wake-up times steady. If late nights carry on without the phone, it’s worth getting the body clock and ADHD looked at.

If you’ve ever stood on the landing at midnight and seen the glow under your teenager’s door, you’ll want to know what this new research says. Teenagers and phones have been blamed for poor sleep for years, but most of the evidence has come from teenagers estimating their own screen time and sleep, which none of us do very accurately. This study is different, and it’s worth understanding properly.

What the study found

Phone use after 10pm was linked to later and shorter sleep

Researchers in the US followed 425 teenagers, average age almost 15, who were part of the Adolescent Brain Cognitive Development (ABCD) Study. An app on each teenager’s Android phone recorded when the phone was in use and a Fitbit recorded their sleep. Nobody had to remember or report anything. The findings were published in JAMA Pediatrics on 19 October 2026.

The team compared each teenager with themselves. On nights when a teenager used their phone after 10pm more than they usually did, they fell asleep about an hour later and slept about 20 minutes less, on average.

Put another way, every extra minute on the phone after 10pm went with sleep starting almost a minute later. Teenagers made some of that back by waking later, but not all of it: each extra minute cost a little under half a minute of sleep. The later in the evening the phone use, the stronger the link, right up to midnight.

The researchers also looked at the last few minutes before sleep. Using the phone right up to the moment of dropping off went with slightly more time awake in the first half hour of the night. The effect was small, less than a minute on average, and had largely faded by the time the gap reached 20 minutes.

How much to trust it

This study is better than most, but it can’t prove the phone is the cause

Two things make this study worth taking seriously. Both phone use and sleep were measured by devices rather than memory. And because each teenager was compared with their own nights, stable differences between families (routines, parenting, personality or a diagnosis such as ADHD) can’t explain the results.

What it can’t do is tell us which came first. You can only use a phone after 10pm while you’re awake, so a teenager who isn’t sleepy will almost always clock up more phone time. Is the phone keeping them awake, or are they awake and reaching for the phone? This design can’t separate the two, and in real life it’s usually some of both.

Other things change from one night to the next too: weekends, homework, a late group chat, caffeine, a lie-in that morning or a worrying day. Fitbits are also better at measuring how long someone sleeps than the exact minute they drop off, which may explain some of that small effect in the first half hour.

It helps to see this alongside earlier work. A review published earlier this year pooled studies that compared young people with themselves. Screen-heavy days came with later bedtimes but not, overall, with less sleep. The new study suggests it’s late-night phone use, rather than screen time in general, that eats into sleep.

Sleep and focus

Lost sleep can make anyone look like they have ADHD

This isn’t only an ADHD story. Anyone who is regularly short of sleep, teenager or adult, starts to struggle in many of the same ways.

Concentration slips, memory gets patchy, tasks take longer and mistakes creep in. Emotions sit closer to the surface, so irritability, tearfulness and snapping at people become more likely. Impulse control weakens too, which makes it even harder to put the phone down the next night.

In teenagers, regularly sleeping less than they need is linked to problems with attention, behaviour and learning, and to a higher risk of accidents, injuries and depression, according to a consensus of sleep medicine experts. A teenager who seems distracted, moody or unmotivated may simply be exhausted, and late-night phone use is often part of the reason.

So when concentration or mood changes, sleep is one of the first things worth looking at, whether or not ADHD is part of the picture. If things ease once sleep improves, that tells you a lot. If they don’t, it’s worth looking deeper.

The same goes for adults. If you’re scrolling past midnight and finding it hard to focus at work the next day, the same cycle may be at play.

The body clock

Teenagers are wired to sleep later, and ADHD can push the clock later still

During puberty the body clock shifts later. Melatonin, the hormone that tells the body it’s night, starts to rise later in the evening, so many teenagers genuinely aren’t sleepy at 10pm. That isn’t laziness or defiance. It’s biology, and it collides with early school starts.

When the clock runs late, the phone fills the gap. A teenager who is always on their phone at midnight may have a body clock that’s running late, not just a phone habit. For some young people this settles into delayed sleep phase syndrome: a lasting pattern of falling asleep very late and struggling to wake, which needs more than a phone rule.

ADHD adds another layer. Sleep problems are common in ADHD, and many young people with ADHD have a body clock that runs later still. A busy mind at bedtime, restlessness and difficulty switching off from something interesting all make the phone harder to put down. Stimulant medication taken too late in the day can delay sleep too. If your teenager has ADHD and bedtime is a battle, raise it with whoever prescribes, because the timing or type of medication can often be adjusted. There’s more in our guide to ADHD and sleep.

ADHD and phones

For many young people with ADHD, the phone is a way to regulate, not just a habit

In clinic, problematic phone and social media use is one of the most common behavioural addictions we see in ADHD. It rarely comes down to willpower. Many young people with ADHD use the phone to regulate themselves: to stimulate a brain that feels flat or restless, or to calm one that feels overloaded after a long day. The research points the same way. A 2022 meta-analysis found more problematic internet use in children and teenagers with ADHD than in their peers without it.

That’s partly why bedtime is so hard. Lying quietly in the dark is exactly the low-stimulation moment an ADHD brain finds difficult, so the phone fills it. Social media also delivers quick, unpredictable rewards, which makes “just five more minutes” especially hard to stop when impulse control is already stretched.

Sleep and ADHD then feed each other. ADHD makes it harder to switch off and fall asleep, and short or broken sleep makes ADHD symptoms worse the next day: attention slips, emotions run hotter and impulses are harder to manage. A tired teenager is more likely to reach for the phone to get through the evening, and the cycle goes round again. A recent review of sleep in young people with ADHD describes ADHD as a 24-hour condition for exactly this reason.

The good news is that breaking the cycle at any point helps. Better sleep tends to make ADHD easier to manage, and treating ADHD well can make sleep easier. Sleep loss on its own can also look a lot like ADHD, which is one more reason a proper assessment matters. That’s why every Sanctum assessment looks at the whole picture as standard: ADHD itself, sleep and addictive behaviours, including phones, gaming and social media.

Why nights are hardest

Bedtime asks the ADHD brain for exactly what it finds hardest

Sleep problems are very common in ADHD. Studies of adults with ADHD put insomnia at between 43% and 80%, and a systematic review found consistent evidence of a later body clock, including melatonin that starts to rise later in the evening. Much of this research is in adults, so it won’t apply to every teenager.

That later clock leaves a gap between “I should go to sleep” and “I actually feel tired”, and the phone fills it. Going to bed then means stopping something rewarding, switching task, keeping track of time and turning stimulation right down. Those are the very skills ADHD makes harder. Many people with ADHD also feel that late evening is the only time that’s truly theirs, which is why you may hear it called revenge bedtime procrastination. It’s a popular term rather than a diagnosis, but many families will recognise it.

Phones are especially hard to walk away from because the feed never ends, the rewards are unpredictable and nothing ever asks you to wait. That matters because people with ADHD tend to find waiting for a reward harder. A meta-analysis of 21 studies found they were more likely than people without ADHD to discount rewards that come later.

Medication can play a part too. As a stimulant wears off in the evening, some young people notice restlessness, racing thoughts or lower mood, just when they most need to organise themselves for bed. If you see this pattern, tell the prescriber.

Small changes that make the phone less tempting

• Put the phone in another room. Distance does more than willpower can at 11pm.
• Use an app blocker. If your teenager chooses one and sets the times themselves, the decision is already made when they’re tired.
• Try greyscale mode. It makes the screen less eye-catching. In a small one-week trial in medical students, it cut screen time by about 28 minutes a day. It hasn’t been tested in teenagers with ADHD, but it’s free and easy to try.
• Swap in something calmer. An audiobook, a low-key podcast, light stretching or a calm puzzle can give the brain something to do without the same pull.

These work because they change the setting rather than relying on willpower. Willpower alone tends to fail here, and that’s down to how the ADHD brain works rather than a lack of motivation.

Advice from the doctor

Work with the ADHD brain, not against it

If your teenager has ADHD, the phone is usually doing a job for them, and how you raise it matters as much as what you say. Rejection sensitive dysphoria (RSD), the intense hurt many people with ADHD feel at anything that sounds like criticism, is very common. Tell a teenager with RSD what to do and it can land as an attack, and they may dig in and oppose the whole conversation. So the best thing you can do is not tell them what to do at all. Help them work it out for themselves.

1. Ask, don’t tell. Find out what the phone does for them at night: does it calm them down, stop them feeling bored, quieten their thoughts or keep them connected to friends? Listen without correcting. The answer tells you what needs replacing, and being asked rather than told keeps them in the conversation.
2. Replace the regulation, not just the device. If the phone calms them, try an audiobook, music or a podcast with the screen off. If they need stimulation, build more movement and activity into the day, which helps both ADHD and sleep.
3. Let them design the plan. Stopping something rewarding is exactly what ADHD makes hard, so don’t rely on willpower at 11pm. Instead, at a calm moment in the day, ask them where the phone could charge overnight and what limits they think would help. A plan they’ve designed is one they’re far more likely to keep.
4. Keep the morning steady. A consistent wake-up time and daylight soon after waking help pull a late body clock earlier. If your teenager takes ADHD medication and sleep is suffering, talk to the prescriber rather than changing the dose or timing yourself.
5. Know when it’s more than a habit. Hiding use, anger or real distress when the phone isn’t available, dropping other interests, falling behind at school or using the phone through the night all suggest it has tipped into something more compulsive. That’s when it’s worth getting help.

If it does turn into a standoff, step back and come back to it another day, at a calm moment rather than at bedtime. Pressure and shame tend to push the behaviour out of sight rather than stop it. Treat it as a problem you’re solving together, with you on their side.

Dr Asad RaffiConsultant Psychiatrist, Sanctum Healthcare

If late nights sit alongside long-standing trouble with attention, organisation or impulsivity, it may be worth looking at the bigger picture. Our free ADHD screener is a quick first step, and our child ADHD assessment page explains what’s involved.

What to do tonight

Agree a plan with your teenager instead of fighting over the phone

Taking a phone away usually starts an argument, and arguments at bedtime don’t help anyone sleep. You’ll get further by agreeing a plan together. These are the changes I’d suggest:

• Charge the phone outside the bedroom, or at least out of reach of the bed. This stops the scroll that carries on right up to sleep.
• Aim for phones down by 10pm on school nights. That’s where this study’s link with later, shorter sleep got stronger.
• Build in a gap before sleep. UK paediatricians’ 2019 screen time guidance suggested a screen-free hour before bed, and it’s still a sensible rule of thumb. Even 20 to 30 minutes is a good start.
• Replace rather than remove. Reading, music, a shower or a podcast with the screen off gives the brain something to do while it winds down.
• Keep wake-up times steady. Try to keep weekend wake-ups within an hour or two of school days and get some daylight soon after waking. Morning light is one of the strongest signals for moving a late body clock earlier.
• Do it as a household. Teenagers notice when the adults are scrolling at midnight too.

Talk to your GP if your teenager regularly can’t fall asleep until the early hours even without their phone, is very hard to wake for school, is falling asleep in lessons or seems low or anxious. Persistent sleep problems are treatable, and they’re usually a sign of something worth understanding rather than a discipline problem.

In summary

Key takeaways

• On nights teenagers used their phones after 10pm more than usual, they fell asleep about an hour later and slept about 20 minutes less.
• Some of the lost sleep was made up by waking later, which is much harder on school mornings.
• The study shows a link, not proof that phones cause poor sleep. Being awake late and being on the phone go together.
• Using the phone right up to sleep went with slightly more wakefulness early in the night, but the effect was under a minute.
• In ADHD the phone is often a way to self-regulate, and sleep and ADHD symptoms feed each other in both directions.
• Phone out of the bed, down by 10pm on school nights and a gap before sleep are sensible steps. Very late sleep that persists without the phone needs a look at the body clock.

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