Correlation between integrated delta and spindle components during nocturnal sleep in mentally retarded children.

The correlation between the integrated delta and spindle components in 81 mentally retarded children (from 3 months to 12 years of age) was studied throughout nocturnal sleep. In 57 (70%, Group A) out of 81 subjects, periodic changes of delta and spindle rhythm powers were noted in the sleep EEG. In 17 subjects (21%, Group B), delta and no-spindle rhythm powers were found, and in the remaining 7 (9%, Group C) no-delta and no-spindle rhythm powers were found throughout nocturnal sleep. A significant increase in abnormal clinical EEGs was found in groups B and C as compared to group A. A significant decrease in DQ was found in groups B and C as compared to group A. A significant decrease in DQ was also found in group C as compared to group B.