Sleep is important in early childhood, when young bodies and minds are developing fast. In the first long-term study of its kind, US researchers confirm findings of previous, shorter studies that show the more time infants and young children spend in front of the TV the less time they spend asleep.
Researchers from Massachusetts General Hospital for Children and Harvard School of Public Health also found that, particularly among minority children, having a TV in the bedroom is also linked to shorter sleep time.
Elsie M. Taveras, associate professor of Population Medicine, and of the Division of Sleep Medicine at Harvard, and colleagues report their findings in the journal Pediatrics.
The team followed more than 1,800 children aged between 6 months and nearly 8 years, who were enrolled with their mothers in a long-term research program called Project Viva, which is investigating numerous factors linked to children's health, starting from before birth.
To provide the data for the study, the children's mothers answered questions when the children were around 6 months old, and then every year for another 7 years.
The mothers gave information about their children's TV viewing habits, such as whether they had a TV in their bedroom, how much time they spent in a room where the TV was switched on when they were babies, and how much TV they watched when they were older.
The mothers were also asked to say how much time on average their children slept every day.
Small but consistent pattern of longer TV viewing tied to shorter sleep
Over the period of the study, every extra hour of TV viewing time was associated with 7 fewer minutes of daily sleep time.
When they analyzed the results, the researchers found a small but consistent link between longer TV time and shorter sleep time.
Over the period of the study, every extra hour of TV viewing time was associated with 7 fewer minutes of daily sleep time, and the link was stronger for boys than for girls.
Ethnic and racial minority youngsters were also more likely to sleep in a room with a TV. Having a TV in the bedroom was linked to a daily sleep time that was on average half an hour a day less than children without a TV in the bedroom.
The researchers say their findings reinforce previous, shorter studies that suggest the longer children spend watching TV - and especially having a TV in their bedroom - shortens the time they spend sleeping, and this is not good for their mental and physical health.
In December 2013, Medical News Today reported a study published in JAMA Pediatrics that found bedroom TVs were linked to childhood obesity. While that study did not investigate links to sleep, the researchers suggested bedroom TVs might disrupt children's sleep patterns, which other studies have linked to weight gain in childhood. They said another reason could be that watching TV in the bedroom increases exposure to child-targeted food advertisements.