There is mounting evidence that poor sleep may not be just a side effect of autism or its treatments, but rather a central feature of it, reports Spectrum News.

Studies over the past few years suggest that sleep problems may stem from the same mutations that underlie other, more characteristic features of autism.

These changes may disrupt the circadian clock, a molecular timer that keeps cells in sync with the night-day cycle. So far, no evidence ties any of the top autism genes to the circadian clock. But several genetic conditions associated with autism, including tuberous sclerosis, fragile X syndrome and Prader-Willi syndrome, may involve mutations that interfere with the clock.

“This is a very active and needed area of investigation,” says Jonathan Lipton, a pediatric neurologist at the Boston Children’s Hospital Sleep Center.