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

The cyclic variation of the integrated delta component in 80 mentally retarded children (from 2 months to 12 years of age) was studied throughout nocturnal sleep, and the following results were obtained. In 62 out of 80 subjects the high integrated delta rhythm power was noted in sleep EEG. In 11 out of the 80, low integrated delta rhythm power was found. In the remaining 7 subjects, no integrated delta rhythm power was found throughout nocturnal sleep. A significant increase in abnormal clinical EEG was found in subjects without delta rhythm power as compared to those with high delta rhythm power. A significant decrease in DQ was found in the subjects without delta rhythm power as compared to those with high and low delta rhythm powers.