A 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, particularly in minority children. Investigators from MassGeneral Hospital for Children (MGHfC) and Harvard School of Public Health (HSPH) report their results in the May issue of Pediatrics.

The study participants, children and their mothers, were enrolled in Project Viva, a long-term investigation of the health effects of several factors during pregnancy and after birth. This study analyzed information–reported by mothers when the children were around 6 months old and then annually for the next 7 years–regarding how much time each day infants were in a room where a television was on, how much time older children watched television daily, whether children ages 4 to 7 slept in a room where a TV was present, and their child’s average daily amount of sleep.

The study revealed that, over the course of the study, each additional hour of television viewing was associated with 7 fewer minutes of sleep daily, with the effects appearing to be stronger in boys than in girls. 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 authors note their results support previous short-term studies finding that both television viewing and sleeping in a room with a television decrease total sleep time, which can have negative effects on mental and physical health.