A new study may have parents thinking twice before they hand over the iPad. 

Researchers at the University of London and King's College London found toddlers' sleep was directly impacted by how much screen time they were given. 

According to the study, the more screen time, the less sleep -- in fact, every hour toddlers spent on iPads and other devices was linked to a sleep decrease of 16 minutes.

The study looked at the habits of more than 700 families -- and is the first to link touchscreen devices directly to sleep. 

Researchers found babies and toddlers who spent more time in front of screens also took longer to fall asleep. The reasons why, the study says, is due to the impact of the "blue light" and how it can change the bodyclock -- causing stimulation that can be difficult to come down from.