Harvard researchers recently published the results of a long-term study showing that watching greater amounts of television is associated with lesser amounts of sleep for children in their infancy and middle childhood.

The investigators found 1,864 children between the ages of six months and eight years to participate in the study through Project Viva, an initiative created in the mid-1990s to help understand a child’s health before or around the time of birth.

“The most exciting part of the study is the longitudinal aspect, showing that these associations start early in life, [and it’s] best to prevent them before behaviors and physiology take hold,” said Matthew W. Gillman ‘76, the principal investigator of Project Viva, an advisor to the other authors of this study, and a professor at Harvard Medical School, the Harvard Pilgrim Health Care Institute, and Harvard School of Public Health.

The co-authors of the television-sleep study, Elizabeth M. Cespedes, Ken P. Kleinman, Shreyl L. Rifas-Shiman, Susan Redline and Elsie M. Taveras, work across HMS, HPHCI, HSPH, Brigham and Women’s Hospital, Beth Israel Deaconess Medical Center, and Massachusetts General Hospital for Children.

Taveras met Gillman in the early 2000s, and after finding that they had many mutual interests, Gillman and Taveras worked side by side for more than 10 years. Taveras and Gillman also worked with Cespedes, a student at Harvard School of Public Health, on the study. The remaining authors had been involved in Project Viva.

“We and others had looked at sleep and television screen time as independent risk factors for child obesity,” Gillman said. “Here we took it a step further by asking, could one of the reasons that more screen time is related to obesity be that it reduces sleep, which itself appears to cause excess weight gain?”

The team worked together to collect annual data from Project Viva and were careful to make sure the association they found between television-viewing and sleep amounts was independent of a child’s age, race/ethnicity, gender, income, or maternal education.

The results of the study showed that, as hypothesized, a greater amount of television screen time may decrease sleeping time. For example, adding one hour of television time daily is associated with a decrease in sleep time of approximately seven minutes.

The presence of a bedroom television was shown to also potentially decrease sleep time, especially in children of racial or ethnic minorities, as it was associated with a 31 minute decrease in sleep for those subjects in comparison with an eight minute decrease in sleep for white, non-Hispanic children.

According to Gillman, “We’ve got a generation of kids whose screen time can veer out of control. One of the adverse health consequences is poorer sleep.”

In order to prevent the consequences of weight gain, lowered mood, and school performance associated with less sleep, the investigators hope to launch interventions based on the results from their study.