Each additional hour of television viewing was associated with seven fewer minutes of sleep daily, researchers found.
The study following more than 1,800 children from ages 6 months to nearly 8 years found a small but consistent association between increased television viewing and shorter sleep duration.
The presence of a television in the room where a child sleeps also was associated with less sleep.
Investigators from MassGeneral Hospital for Children (MGHfC) and Harvard School of Public Health (HSPH) are the first to examine the connection between television and sleep duration over several years.
More From This Section
The study analysed information - reported by mothers when the children were around 6 months old and then annually for the next seven years - regarding how much time each day infants were in a room where a television was on.
It also analysed how much time older children watched television daily, whether kids aged 4 to 7 slept in a room where a TV was present and their child's average daily amount of sleep.
Racial and ethnic minority children were much more likely to sleep in a room where a television was present, and among those children, the presence of a bedroom television reduced average sleep around a half-hour per day.
The study appears in the journal Pediatrics.