Children with no set bedtime pattern are more likely to have behavioural problems, say researchers at University College London. But, they add, give the child a set bedtime and these problems can be reversed.
Studying the effects of irregular bedtimes in three, five and seven-year-old children, the researchers found that irregular bedtimes cause children to have mood swings and become hyperactive. This is because their body clocks are being “messed up”, according to study leader Yvonne Kelly.
The sleep habits of more than 10,000 children, gathered by data from the UK Millennium Cohort Study, were analysed, and the researchers surveyed parents about their children’s sleep and behavioural problems. (Children with attention deficit disorder or an autism spectrum disorder were not part of the study.)
Around 20% of parents said their three-year-olds never went to bed at a consistent time. This figure dropped to 9% for five-year-olds and 8% for seven-year-olds.
Those who went to bed at irregular times had the most behavioural problems. But when they switched to a routine, their behaviour problems were reversed.
“Not having fixed bedtimes, accompanied by a constant sense of flux, induces a state of body and mind akin to jet lag and this matters for healthy development and daily functioning,” Kelly said.
“It follows that disruptions to sleep, especially if they occur at key times in development, could have important lifelong impacts on health.
“What we’ve shown is that these effects build up incrementally over childhood, so that children who always had irregular bedtimes were worse off than those children who did have a regular bedtime at one or two of the ages when they were surveyed.”