Screen Time Before Bed and Toddler Sleep: What a 2024 Randomized Trial Proves

The 2024 randomized trial: what happens when you actually remove the screen

*A randomized clinical trial published in JAMA Pediatrics in 2024 finally tested this directly — and found that reducing screen time before bed causally improved toddler sleep quality, measured objectively rather than by parent report.*

Researchers at King's College London, working with families across the UK, ran this randomized controlled trial with toddlers aged 16 to 30 months who typically had 10 minutes or more of screen time in the hour before bed on at least 3 days a week (DOI: 10.1001/jamapediatrics.2024.3997). Families were randomly assigned to either remove screen time in that pre-bed hour or continue their usual routine. Sleep was tracked with actigraphy — a wearable movement sensor — not just parent diaries. The screen-time-removal group showed small-to-medium improvements in objective sleep quality and efficiency, fewer night awakenings, and shorter daytime naps compared to the control group, pointing to genuinely better sleep once the screen was gone. Interestingly, the trial found no measurable effect on daytime attention, so the benefit was specific to nighttime sleep, not a general improvement across the board.

This is what makes the trial important: it's the first study on this exact age group and time window to move from "screens and poor sleep show up together" to "removing the screen actually changes sleep, measurably." A parent-administered intervention this simple, tested with objective sleep data, is rare in infant sleep research.

Why children's eyes react differently to evening light

Beyond the direct trial evidence, there's a biological reason young children may be more vulnerable to screen light than adults: their eyes let far more of it through.

A study comparing melatonin suppression in children and adults exposed to the same evening light found the effect was significantly stronger in children (DOI: 10.1210/jc.2014-1629). A child's lens is still immature and filters much less light before it reaches the retina — a protective mechanism that only fully develops years later. That's a plausible mechanism behind the JAMA Pediatrics trial's results: the same screen time may genuinely hit a toddler's circadian rhythms harder than it would an adult's sleep-wake cycle.

Pediatric sleep specialists have long suspected that blue light affects children more than adults, and this is one plausible reason why: the same blue light exposure reaches deeper into a young child's eye. Limiting screen time, avoiding screen time altogether isn't necessary, or simply going without screen for the final stretch before bed, all lean on this same idea — reduce blue light exposure late in the day and the production of melatonin can proceed on schedule.

Reading tiredness cues matters too

Whichever screen-time rule you set, timing bedtime to actual tiredness cues — eye rubbing, yawning, a glazed stare — reduces the overtiredness that makes falling asleep harder regardless of what happened on a screen earlier in the evening.

How much screen-free time before bed actually helps

The trial tested removing screens in the single hour before bedtime — a modest, achievable target rather than a full evening screen ban.

A few practical takeaways from the evidence above:

• One hour before bedtime with less screen time is the window the 2024 trial actually tested and found effective for better sleep in children — a realistic target for most families, not an all-day restriction. You don't need to avoid screen time entirely to see the benefit shown in the trial.
• Handheld screens (tablets, phones) matter most: they're held close to the face, unlike a TV watched at a distance in an otherwise dim room.
• "Night mode" filters aren't a full substitute for cutting screen time: they reduce some blue light but don't address the show's stimulating content or the screen's overall brightness, both of which delay settling.
• Consistency matters as much as the exact minute count: the trial's effect on sleep quality held up over weeks, suggesting the nighttime routine itself, not a single night, is what shifts sleep.

Building healthy screen habits, not just a bedtime rule

A one-hour screen curfew is easier to sustain when it sits inside broader healthy screen habits rather than standing alone as a single, isolated rule. Pediatric guidelines generally distinguish daytime screen time, which is more about limiting sedentary time and passive screen time overall, from evening screen time, which is specifically about protecting the sleep-wake cycle. Framing it as boundaries around screen use — a consistent electronic-devices cutoff every evening — tends to stick better than an occasional, inconsistently enforced ban on device use. The relationship between screen time and total sleep in toddlers is strongest for this evening window, so reducing screen time there, more than avoiding screen time altogether, is what seems to promote better sleep and healthy sleep habits overall.

Not every family needs to eliminate excessive screen time everywhere at once. Even modest, consistent steps to reduce screen time in the hour before bed — rather than chasing perfect sleep quantity and quality overnight — line up with what the trial actually tested and found effective.

A screen-free wind-down that works

Swapping the pre-bed screen for a calm, dim activity is the simplest lever, and it works best done at the same time every night.

• A picture book read under warm, dim light rather than a backlit tablet.
• A bath followed by a gentle massage, which lowers body temperature and supports sleep onset without any bright light exposure.
• A lullaby or a told story, in a room lit with warm amber or red light rather than white or blue — these wavelengths suppress melatonin far less.
• A consistent [bedtime routine](/blog/baby-bedtime-routine) that signals sleep is coming, independent of any screen.

A calm, dark sleep environment paired with this screen-free hour helps your baby fall asleep faster and sleep longer — no gadget required to get there.

How to introduce a screen curfew without a fight

Replacing screen time gradually, rather than avoiding screen time all at once, tends to work better for both toddler sleep behavior and parental sanity.

A few pointers on how screen time affects sleep in practice, and how to act on it:

• Start with the last 30 minutes, then extend it. Cutting daily screen time cold turkey to a full evening-free routine can backfire; reduced screen time introduced gradually gives everyone time to adjust their evening routine.
• Distinguish passive screen time from interactive use. Passive screen media — a calm show watched at a distance — appears to interfere with sleep less than an interactive game or video call held close to the face, even though neither is ideal right before bed.
• Swap the device, don't just remove it. Toddlers who lose their tablet with nothing to replace it often protest harder; handing over a book or a soft toy at the same moment smooths the transition and avoids turning the curfew into a nightly battle.
• Watch for downstream signs of poor sleep, like more frequent night wakings, a harder time falling asleep, or shifts in daytime mood, which can signal that screen exposure earlier in the evening is still creeping into the wind-down window.
• Keep the bedroom itself calm, not just the last activity before it: a caregiver who dims the lights and keeps the bedroom free of screens makes the curfew easier to hold to than a bright, stimulating room right up until lights-out.
• Remember this is about nighttime sleep, not total technology use. The trial only measured evening screen time; daytime screen use for learning or play wasn't part of what researchers tested, so a sensible boundary around screen use in the evening doesn't require banning devices earlier in the day.

None of this requires perfection. Even a partial, consistent reduction in evening screen exposure was enough to produce a measurable improvement in sleep in the trial — a realistic bar for most families juggling toddler sleep, work, and everything in between.

Getting enough sleep matters more than any single tactic: the goal of setting boundaries around screen use isn't to police every minute of electronic devices, it's to protect the time to sleep that toddlers actually need — a key part of overall sleep health. If your child's sleep or children's sleep more broadly still seems disrupted sleep after a few weeks of a consistent screen curfew, or if you notice ongoing problems in toddlers' sleep alongside daytime irritability, it's worth discussing with your pediatrician rather than assuming a smartphone screen or tablet is automatically to blame — excessive screen time is one factor among several that can affect the role of sleep in a toddler's day, including illness, teething, or a nap schedule that no longer fits their age.

FAQ

Does the 2024 study prove screens cause worse sleep, or just correlate with it?

It's the first randomized trial on this exact question in toddlers: parents were assigned to remove screens in the hour before bed or continue as usual, and objective sleep tracking showed small-to-medium improvements in sleep efficiency and night awakenings in the removal group — evidence of a causal effect, not just a correlation.

How much screen-free time before bed made a difference in the trial?

The trial tested removing screens in the hour before bedtime for toddlers who typically had 10+ minutes of screen use in that window. Many pediatric guidelines recommend 60 to 120 minutes screen-free before bed.

Does this apply to TV, or just tablets and phones?

The trial focused on handheld screens (tablets, phones), which are held close to the face. TV watched at a distance in an otherwise dim room appears to have a smaller effect, though the same wind-down principle applies.

Why are babies more sensitive to screen light than adults?

A baby's lens is far more transparent than an adult's, filtering out much less blue light before it reaches the retina. A study comparing children and adults found significantly greater melatonin suppression in children exposed to the same evening light.

Does cutting evening screen time also improve daytime naps?

In the 2024 trial, toddlers in the screen-removal group had shorter daytime sleep for toddlers alongside better nighttime sleep duration — consistent with a healthier overall sleep cycle rather than daytime sleep simply making up for a poor night. It's a sign of improvement in sleep patterns overall, and evidence that unchecked screen time can lead to compensatory daytime napping, not just one better night.

Does how screen time affects kids' sleep differ much between children?

Some variation is expected — the trial reported small-to-medium average effects, not a uniform result for every child. Building better sleep habits around a consistent evening routine matters as much as the exact screen cutoff for most families.

Can the Mothair device help during a screen-free wind-down?

Yes. The Mothair wellness device produces gentle sounds and vibrations that recreate the sensory environment of the womb, helping your baby settle into a calm bedtime routine without any screen. Mothair is a wellness device and does not replace medical advice — consult your pediatrician about your baby's sleep.

Mothair wellness reminder: Mothair is a wellness device — it does not replace medical advice. Every baby responds differently to their evening environment. The information in this article is general and is not pediatric advice. Consult your doctor or pediatrician for any question about your baby's sleep.