“A greater number of hours watching television is associated with less sleep hours in preschool and school age children”
According to the literature children who watch TV before bedtime are more reluctant to go to bed. Studies have shown that the violent content of some programs can alter the quality and quantity of sleep especially in children of eight years and younger because of the difficulty that these may have to discriminate between reality and fiction. Another possible explanation that has been suggested is that being exposed to bright screen before going to bed can produce a reduction in the secretion of melatonin which is considered a hormone that regulates sleep. In previous studies the inadequate number of sleep hours has been associated with an increased risk of psychiatric problems, overweight, obesity and poor academic performance in children and adolescents. The aim of this INMA study was to examine the potential association between the number of hours that a child watches television and the number of hours of sleep on preschool and school children in three of the INMA cohorts (Menorca, Sabadell and Valencia). This is the first study that has examined the association between the length of time watching television and duration of sleep time in children.
The study found that the higher the number of hours a child spent watching TV, the less hours were spent sleeping. Moreover, as both parameters were measured twice during the time of study, the study confirmed that when a child increased the number of hours watching TV the number of hours that the child had slept also decreased. On weekends it was observed a reduction of this effect and this fact was attributed to the reduction of stress of the child during the weekend. Also, unlike other studies, researchers did not observed any relationship between television watching and hyperactivity or inattention problems (that would have indirectly explained the observed effect of fewer hours of sleep). This large study (1713 children) took into account factors that may have confounded the association between hours of television watching and hours of sleep, such as some maternal factors (IQ or mental problems) or some factors of the child (hyperactivity or inattention problems). The study provides consistent evidence of the effects of watching TV on sleep in children and therefore supports the regulation of TV watching in young children, especially in the previous hours of going to bed.
ReferencE: Marinelli M, Sunyer J, Alvarez-Pedrerol M, Iñiguez C, Torrent M, Vioque J, Turner MC, Julvez J. Hours of Television Viewing and Sleep Duration in Children: A Multicenter Birth Cohort Study. JAMA Pediatr. 2014 May;168(5):458-64.