Teens Are Sleep-Deprived, And Screens Are Why, Study Suggests - beginning in 2009 when smartphone use became widespread, there was a 17% increase of students reporting sleeping 7 hours or less per night, which sleep experts term as insufficient.

See the source article by following the link below:
Teens Are Sleep-Deprived, And Screens Are Why, Study Suggests - beginning in 2009 when smartphone use became widespread, there was a 17% increase of students reporting sleeping 7 hours or less per night, which sleep experts term as insufficient.