Canadian researchers discovered a night of poor sleep significantly decreases performance on intelligence tests in children with autism spectrum disorder (ASD) and also in neurotypical children (without ASD).
Researchers at the Hôpital Rivière-des-Prairies in Montreal found that 45 percent to 85 percent have sleep problems as compared to 10 to 25 percent of neurotypical children (children with a mean age of 10 years old without an intellectual deficiency or sleep problem and who were not on medication).
In the study, researchers observed the EEG measures of 13 autistic children and 13 neurotypical children and found that disruptions in protective brain waves during sleep are associated with lower results on verbal IQ tests.
The brain waves demonstrating good sleep consolidation in these children were measured in a laboratory. These markers of light sleep known as “sleep spindles” occur during a sleep phase that repeats throughout the night in which body metabolism slows and the brain rests (contrary to rapid eye movement sleep, when the brain is active and dreams).
“We observed that the more a child had these waves throughout the night, the better the child was at cognitive tasks, particularly the Wechsler Intelligence Scale for Children,” said first author Sophie Tessier, a doctoral student in the Sleep Research Laboratory.
It also appears that the quality of sleep over the whole night, and not only before midnight or at the end of the night, promotes good intellectual functioning. These observations apply for both groups of children.
However, despite these similarities, the researchers noted that the relationship between these sleep waves and cognitive performance differs between neurotypical and autistic children, as different brain regions are involved for each group.
“This is an important discovery that confirms the major role of sleep in consolidating cognitive abilities,” explained Roger Godbout, the director of the Sleep Research Laboratory at the hospital, affiliated with the Institut universitaire en santé mentale de Montréal and Université de Montréal.
“This study establishes beyond a doubt that children and adolescents are particularly affected by a lack of sleep, especially because they are in an important developmental period.”
Researchers believe their findings confirm the crucial role of sleep in cognitive development, and also opens the way to more accurate treatment for sleep disorders in youth.