The study in Scientific Reports suggests every hour spent using a touchscreen each day was linked to 15 minutes less sleep.
However, those playing with touchscreens do develop their fine motor skills more quickly.
Experts said the study was "timely" but parents should not lose sleep over it.
There has been an explosion in touchscreens in the home, but understanding their impact on early childhood development has been lacking.
The study by Birkbeck, University of London, questioned 715 parents of children under three years old.