The research, which appeared in the US journal Pediatrics on Monday, found that lifelong problems could result from erratic childhood bedtimes, but that the effects could be reversed with implementation of a schedule.
"Not having fixed bedtimes, accompanied by a constant sense of flux, induces a state of body and mind akin to jet lag," said Yvonne Kelly of the University College London.
Inconsistent bedtimes can disrupt natural body rhythms and cause sleep deprivation, impairing brain development and the ability to regulate some behaviors, the research showed.
"We know that early child development has profound influences on health and wellbeing across the life course," Kelly said.
The British study analyzed the bedtime data of more than 10,000 children of ages three, five and seven, taking into account their behavioral problems as reported by teachers and mothers.
Hyperactivity, conduct issues, problems with peers and emotional difficulties were some of the conditions that were worse for children with irregular bedtimes.
"One way to try and prevent this would be for health care providers to check for sleep disruptions as part of routine health care visits," Kelly said.
Problems, however, only became more severe as children progressed through childhood. And those who adopted a more stable bedtime schedule demonstrated clear improvements in behavior.
Three-year-olds were the most likely to go to bed at irregular hours, with one in five going to sleep at erratic times.
Children with varying bedtimes or who went to bed after 9 pm were more likely to be from a socially disadvantaged background, a factor the study took into account.