Most parents don’t seem to be too worried about letting young children play with tablets and smartphones for just about as long as they like. Kids are literally born with screens in front of their faces, using the devices by themselves by the age of three.

But a new study, the first of its kind, has found a distinct connection between toddler use of touch-screen devices and a loss of sleep.

Researchers lead by Tim Smith, a lecturer in cognitive psychology at Birkbeck, University of London, reviewed online questionnaires completed by more than 700 UK families, Live Science reports. The questionnaire asked parents how much time their children spent with a smartphone or tablet in a given day along with how much sleep their children get, how many times they wake up at night, and how long it usually takes them to fall asleep.

Children 6 to 11 months old were reported to use touch-screen devices an average of 8 minutes a day compared to 19 minutes for children 12 to 18 months old. Touch-screen devices were used an average of 25 minutes a day by children 19 to 25 months old, which was a little more than half the amount of time 2-year-old children spent on touch-screen devices each day.

The research team found that the children who used touch-screen devices more often took longer to fall asleep, slept more during the day, and got less sleep overall compared to children who used such devices less frequently. Each additional hour of time spent on a device was associated with 26 fewer minutes of sleep at night and 11 more minutes of sleep during the day, which comes out to a total of 15.6 minutes less total sleep.

It’s worth noting that these numbers would likely be much higher if the study had been conducted in the US, where 96.6% of children in a smaller study were discovered to start using mobile devices before the age of one.

The University of London team hypothesized that the devices are interfering with the time traditionally used to fall asleep, possibly making sleep seem less desirable. Children who use touch-screen devices at night might also experience more difficulty falling asleep due to excessive mental and physiological stimulation, Smith added.

The study did not examine whether the reduced sleep was impacting the children’s health or cognitive development but the team intends to answer these questions in future studies related to long-term effects of touch-screen devices in adolescents. Smith recommends that toddlers refrain from using tablets and smartphones in their last hour before bed.

These devices might very well be attributed to the sleep problems of adults as well.

Statistics reported by the CDC last year found that one-third of Americans aren’t getting seven or more hours of sleep per day. In 2015, a YouGov.com poll revealed that 38% of Americans felt they aren’t getting enough sleep at least four days a week.

According to NPR, these findings might be attributed to a lack of what sleep experts call “sleep hygiene.” This refers to the habits that impact how well you sleep and how alert you are during the day. Habits that decrease sleep hygiene include a lack of exercise, excessive caffeine consumption, and the use of smartphones and tablets in the last two hours before bed. Two major elements of a healthy sleep-wake cycle are not only limiting exposure to light to the day but making sure most of this light is natural. The bedroom, experts say, should be as relaxing as possible, i.e. completely removed from devices that could easily interrupt a regular nightly routine that is essential for helping the body recognize when it’s time for sleep.