The topology of performance curves during 72 hours of sleep loss: A memory and search task

Three levels of working memory load of a visual search (Memory and Search) task were tested in a 72-hour sleep deprivation paradigm. General performance and accuracy decrease over time with monotonic and rhythmic components. The signal detection discriminability index, d', decreases monotonically with rhythmic variations. The index of response bias, β, shows no monotonic trend, but significant circadian rhythmicity. The extent of the monotonic and rhythmic changes in accuracy and in d' is directly related to the level of working memory load. The amplitude of the circadian component of accuracy and d' is enhanced for the higher levels of working memory load. The implication of potentiated circadian rhythmicity as a function of cumulative sleep loss is discussed.