Automated measurement of alpha, beta, sigma, and theta burst characteristics.

An automatic system was used for the selection and analysis of alpha, beta, and theta waveforms occurring in the awake and REM sleep states and sleep spindles occurring in stage 2 sleep. Two nights of sleep were analyzed for each of five normal subjects in each of five age groups: 3--5; 13; 25--34; 43--53; and 67--79 years of age. The waveform frequencies, length, and rate of occurrence were measured. No age-related changes were found in the alpha frequency (except for the younger group). No significant age differences were found in the beta and theta frequencies in the awake state. During REM sleep, the average beta and theta frequencies of the two youngest groups were significantly different from those of the three older groups. The average frequency of stage 2 sleep spindles of the two youngest groups was less than that in the middle group; the average spindle frequency of this group was significantly less than that of the two older groups. The number of spindles per minute was significantly less for the younger group and significantly more for the 25- to 34-year-olds.