Principal component scoring of the resting EEG spectrum provides further evidence for age‐associated disinhibition of the wake drive

Background: Aging is often accompanied by increasingly occurrence of profound sleep‐wake disturbances. However, normal ‘sleep aging’ can also be advantageous to older people, for example, they have a better ability to tolerate sleep deprivation than to younger people. In previous work, we compared the principal component structure of the electroencephalographic (EEG) spectra of Non‐Rapid‐Eye‐Movement (NREM) sleep in young and elderly people, and found that the decrease in slow‐wave activity, which is the most earliest and most obvious age‐related modification of the sleep EEG spectrum, can be viewed as a consequence of a reduced rise of the first principal component score combined with an insufficient fall of the second principal component score. It was suggested that such changes in principal component scores can be caused by disinhibition (i.e. strengthening) of the wake drive due to weakening of the sleep drive. It is possible that the second principal component score remains higher in older people compared to younger people not only during NREM sleep, but also during normal and extended wakefulness. Methods: To test this suggestion, principal component analysis was applied to the spectra of resting EEG signals obtained with a three‐hour interval during the course of sustained wakefulness of 130 and 33 participants of two independent sleep deprivation experiments. Results: The second principal component score was positively linked to participants' age. Conclusions: Elevation of score can reflect age‐associated strengthening of the sleep drive, which predisposes older people to develop certain disturbances of their sleep‐wake cycle and, on the other hand, to tolerate sleep deprivation better than younger people.