Cyclic variation of integrated spindle components during nocturnal sleep in mentally retarded children.

The cyclic variation of the integrated spindle component in 77 mentally retarded children (from 3 months to 12 years of age) was studied throughout nocturnal sleep. In 31 out of 77 subjects high integrated spindle rhythm power was noted in the sleep EEG. In 24 subjects, low integrated spindle rhythm power was found, and in the remaining 22 subjects no integrated spindle rhythm power was noted throughout nocturnal sleep. There was a significant increase in abnormal clinical EEGs in subjects with no spindle rhythm power as compared to those with high and low spindle rhythm powers. A significant decrease in DQ was found in the subjects with no spindle rhythm power as compared to those with high and low spindle rhythm powers.