Children with irregular bedtimes may be more prone to having behavioral problems, according to a new study. Reported by CBS News, research published on Oct. 14 on the official website of the American Academy of Pediatrics showed that not going to bed at a regular time each night could interrupt a child\'s natural circadian rhythm, leading to lack of sleep. This in turn could affect how the brain matures and how kids are able to control certain behaviors. The National Sleep Foundation suggests that preschoolers between 3 and 5 years old get about 11 to 13 hours of sleep a night, while kids up to the age of 12 need around 10 to 11 hours of nightly shut-eye. For the study, researchers looked at data from 10,230 7-year-olds who were enrolled in the U.K. Millennium Cohort Study. Data was collected from them at ages 3, 5 and 7, and their behavior was rated by their mothers and teachers. Bedtime problems were most common at age 3, with one in five children going to bed a different time each night. About 9 percent of kids had irregular bedtimes when they were 5, and only 8.2 percent slept at different times each night by the time they turned 7 years old. By age 7, most of the kids regularly went to bed between 7:30 and 8:30 p.m. Children who had irregular bedtimes or went to bed after 9 p.m. were more likely from socially-disadvantaged backgrounds. Kids who went through early childhood without a set bedtime had more hyperactivity, conduct problems, problems with other people their age and emotional difficulties. Those who were put on a regular schedule had more improvements in these behavioral areas.