Sleepwalking may run in family

• Over 60 % of sleepwalkers’ children develop the disorder

• Sleepwalking is a common childhood disorder

• Generally, it disappears during adolescence

• Sleep terror disorder marked by scream and fear

Toronto: Children are seven times more likely to sleepwalk if both their parents have a history of sleepwalking, according to a new study.

More than 60 per cent of children developed sleepwalking when both their parents were sleepwalkers in a study among kids born in the Canadian province of Quebec, researchers said.

The study also found that children with one parent who was a sleepwalker had three times the odds of becoming a sleepwalker compared with children whose parents did not sleepwalk.

Sleepwalking is a common childhood sleep disorder that usually disappears during adolescence. Sleep terrors are another early childhood sleep disorder often characterised by a scream, intense fear and a prolonged period of inconsolability.

The two disorders (also known as parasomnias) share many of the same characteristics and arise mainly from slow-wave sleep, according to the study.

Jacques Montplaisir, of the Hopital du Sacre-Coeur de Montreal and team analysed sleep data from a group of 1,940 children born in Quebec in 1997 and 1998 and studied in 1999 to 2011.

The authors found an overall childhood prevalence of sleep terrors (ages one and a half to 13 years) of 56.2 per cent. There was a high prevalence of sleep terrors (34.4 per cent) at one and a half years of age but that prevalence decreased to 5.3 per cent at age 13.

The overall childhood prevalence of sleepwalking (ages two and a half to 13 years) was 29.1 per cent. Sleepwalking was relatively infrequent during the preschool years but the prevalence increased steadily to 13.4 per cent by age 10 years.

Study results showed that children who had sleep terrors during early childhood were more likely to develop sleepwalking later in childhood at age 5 years or older than children who did not experience sleep terrors in early childhood (34.4 per cent vs 21.7 per cent).

"These findings point to a strong genetic influence on sleepwalking and, to a lesser degree, sleep terrors. This effect may occur through polymorphisms in the genes involved in slow-wave sleep generation or sleep depth," researchers said.