Ontogeny of delta activity during human sleep.

The study describes the ontogenetic and time-related changes in peak amplitude, frequency, and incidence of delta waves of twenty-five normal subjects between the ages of 3 and 79 years of age. All slow waves greater then 5 muV in magnitude and between 0.5 and 3.0 c/sec were analyzed for the first 6 h of the night's sleep. In this study increasing age was accompanied by decreases in average peak amplitude of delta waves over 5 muV, slowing of delta frequencies, and decreases in incidence of waves greater than 20 muV. Across 2-h epochs of the night there were tendencies for the average peak amplitude of delta waves to decrease, for the average frequency for a given amplitude range to decrease, and for the incidence of low-amplitude delta waves to increase and high-amplitude waves to decrease. The incidence of waves greater than 5 muV remained constant across ages and epochs. Frontal channel delta waves exhibited an age-group difference whereas no such difference was apparent for central channel delta activity, suggesting that the frontal channel may possess advantages over the central because of greater sensitivity to age related changes.