One-year-olds are busy little bodies. They may know just a handful of words, but if they are typical, they’re on the cusp of learning many more.

If they aren’t toddling yet, they’re about to be. They are active. They want to turn the pictures in the board book, to topple the tower of blocks or to do anything themselves.

If instead they spend more than two hours a day in front of screens — any type of screen, whether it’s television, mom’s mobile phone, a tablet or any other digital device — they stand a far bigger chance of running into developmental delays as they grow.

That finding comes from researchers in Japan who studied data from more than 7,000 children. Kids with up to two hours of daily screen time by age 1 were 61% more likely to have delayed communication skills by age 2 than were 1-year-olds who watched less than an hour a day.

The researchers said 1-year-olds who logged more than four hours had a developmental-delay risk nearly five times greater than children who had minimal screen time.

Most of the delays were in communication and problem-solving skills. But the study also found delays in toddlers’ personal and social skills, and even motor skills like finger-wiggling.

The study made no distinction between educational and other types of screen time.

Parenting is a tough job. Handing over a smartphone to a squirmy baby to be played with (or gnawed on) while you get them into a suitable outfit can be pragmatic. But in general, pediatric health experts say the less screen time, the better.

And wouldn’t you rather enjoy the quiet? Too much screen time isn’t healthy for adults, either.