Children who do not have a regular bedtime may be more likely to have problems with their behaviour, such as hyperactivity and emotional difficulties, a new study has found.

UK scientists analysed data on over 10,000 children. Information on their bedtime routines was collected when the children were aged three, five and seven. Behavioural problems were reported by the children's mothers and teachers.

The study found a statistically significant link between irregular bedtimes and behavioural issues, including hyperactivity, conduct problems, difficulties with peers and difficulties with emotions.

Irregular bedtimes appeared to disrupt the circadian rhythm - the body's internal clock - which led to sleep deprivation. This affected development of the brain, specifically undermining maturation and the ability to regulate certain types of behaviour.

According to Prof Yvonne Kelly of University College London, it is already known that early development has a major influence on health and wellbeing throughout life.

"It follows that disruptions to sleep, especially if they occur at key times in development, could have important lifelong impacts on health...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," she explained.

The study noted that children's behaviour worsened as they got older if they continued to have an irregular bedtime. However, if a regular bedtime was introduced, behaviour improved.

"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.

"But our findings suggest the effects are reversible. For example, children who change from not having to having regular bedtimes show improvements in their behaviour," Prof Kelly noted.

The study found that children were most likely to have an irregular bedtime at the age of three. By the age of seven, more than 50% of the children regularly went to bed between 7.30pm and 8.30pm.

The study also found that children with irregular bedtimes or those who went to bed after 9pm were more likely to come from disadvantaged homes.

Details of these findings are published in the journal, Pediatrics.