Children with autism can have difficulties with communication skills, social interaction and repetitive patterns of behavior. Might they have difficulties with sleeping patterns as well?
A recent study found that children with autism slept less on average each night than children without autism.
The differences ranged from 15 minutes to nearly 45 minutes each night, depending on the children's ages.
The differences did not show up when the children were babies, but they began showing up in toddlerhood.
This study, led by Joanna Humphreys, MD, of the Hospital for Sick Children in Toronto, Canada, looked at the long-term sleep patterns of children with autism.
The researchers used data from an ongoing study in which 73 children had been diagnosed with an autism spectrum disorder (ASD) by age 11. The original ongoing study had a total of 14,062 children born in 1991 and 1992.
The parents had reported on the children's sleeping habits in questionnaires eight times from when the children were 6 months old to 11 years old.
The researchers compared how long the children with autism slept to how long the children without ASD slept each night.
The results revealed that the children with autism slept approximately 17 to 43 minutes less per day between the ages of 2.5 and 11 years old.
These differences remained after the researchers had taken into account differences that might occur based on sex, race/ethnicity, epilepsy diagnosis and a greater number of siblings.
There were no differences regarding the length of the children's sleep, with or without autism, when the parents had been asked about their children's sleep at 6 months and 18 months of age.
The differences only began showing up when the parents were asked at the check-up when the children were 2.5 years old.
The lesser amount of sleep among children with autism occurred only during their nighttime sleep, not during any daytime naps.
The children with autism tended to have later bedtimes and tended to wake up a little earlier.
For example, 2.5-year-old autistic children slept an average 17 minutes less each night than non-autistic children.
At age 3.5, the autistic children slept an average 28 minutes less than non-autistic children.
The gap widened to 30 minutes when the children were nearly 6 years old and to 43 minutes when the children were nearly 7.
The lesser amount of sleep among autistic children was 26 minutes at age 9 and 20 minutes at age 11.
Children with autism spectrum disorders were also more likely than non-autistic children to wake up at least three times during the night.
While about 13 percent of the autistic children woke up at least three times a night when they were 2.5 years old, only 5 percent of the non-autistic children did at that age.
By the time the children were nearly 7, only 0.5 percent of the non-autistic children were waking up three times a night, compared to 11 percent of the autistic children.
Children between 18 months and 2.5 years of age who began sleeping less each night than the average amount for 70 percent of all children were more likely to be diagnosed with autism later.
The same was true for children who slept less than the broad average range for children between ages 2.5 and 3.5 years old.
The researchers suggested that the differences in sleep in autistic children may be related to brain differences that also affect their biological clocks.
"This research emphasizes the importance of assessing sleep disturbances early in children with autism spectrum disorders, to offer support and anticipatory guidance to parents and to consider the use of melatonin to reduce sleep latency," the researchers wrote.
Sleep latency refers to how long it takes a person to fall asleep.
William Kohler, MD, the medical director of the Florida Sleep Institute in Spring Hill, Florida, said past research has shown a link between sleep problems and a subset of children with autism.
"Previous studies have shown that 44 to 83 percent of children with autism spectrum disorders have significant sleep problems, though not all children with autism spectrum disorders do," he said.
"The other studies have shown that the good sleepers have less behavior problems and less affective problems than the poor sleepers," Dr. Kohler said. "So the correlation in the previous studies is that the poor sleepers were more likely to have affective problems."
This study was published September 30 in the journal Archives of Disease in Childhood. The research was funded by Guy's and St. Thomas' Charity. The authors declared no conflicts of interest.