The effects of age and gender on sleep EEG power spectral density in the middle years of life (ages 20-60 years old)

The effects of age and gender on sleep EEG power spectral density were asse ssed in a group of 100 subjects aged 20 to 60 years. We propose a new stati stical strategy (mixed-model using fixed-knot regression splines) to analyz e quantitative EEG measures. The effect of gender varied according to frequ ency, but no interactions emerged between age and gender, suggesting that t he aging process does not differentially influence men and women. Women had higher power density than men in delta, theta, low alpha, and high spindle frequency range. The effect of age Varied according to frequency and acros s the night. The decrease in power with age was not restricted to slow-wave activity, but also included theta and sigma activity. With increasing age, the attenuation over the night in power density between 1.25 and 8.00) Hz diminished, and the rise in power between 12.25 and 14.00 Hz across the nig ht decreased. increasing age was associated with higher power in the beta r ange. These results suggest that increasing age may be related to an attenu ation of homeostatic sleep pressure and to an increase in cortical activati on during sleep.