THE EFFECTS OF SLEEP LOSS ON TASK-PERFORMANCE AND THE ELECTROENCEPHALOGRAM IN GROUP AND ELDERLY SUBJECTS

The effects of 28-h sleep loss on performance, reaction time (RT) dist ribution functions, and spectral composition of the EEG were evaluated in three choice-RT tasks for young (N = 12, aged 18-24 years) and old (N = 12, aged 62-73 years) subjects. Manipulations of stimulus degrad ation, stimulus-response compatibility, and interstimulus interval var iability were to affect encoding, response selection, and motor adjust ment stages, respectively. In order to discriminate between independen t variables that were presumed to be computational or energetical in n ature, effects on EEG spectra and PT-distributions were studied. Spect ra of the EEG indicated higher cortical arousal levels for the elderly than for the young. The most dramatic effect of sleep loss on perform ance was a marked increase in the number of omitted responses. This ef fect was smaller for the elderly than for the young. The results sugge st that the detrimental effects of sleep loss are smaller in the elder ly, which is consistent with an inverted-U relationship between arousa l and performance. The age effects on the processing stages were mainl y limited to response selection. (C) 1997 Elsevier Science B.V.