THE EFFECTS OF CHRONIC SLEEP REDUCTION ON THE PERFORMANCE OF COGNITIVE TASKS SENSITIVE TO SLEEP-DEPRIVATION

In four sleep loss experiments we aimed, first, to compare performance during long-term sleep reduction with performance during short-term t otal sleep deprivation, and second, to measure the effects of both met hods of sleep loss on ability to ignore distracting irrelevant stimuli , using a finding embedded figures test (FEFT). Logical reasoning, aud itory vigilance and finding embedded figures tasks were shown to be si gnificantly sensitive to one night's sleep deprivation. However, in on e sleep reduction study subjects reduced to a mean of 5.2 hours sleep per night for 4 weeks showed no performance deficits on logical reason ing. In a second sleep reduction study subjects reduced to a mean of 4 .3 hours sleep per night for 4 nights, and subjects reduced to a mean of 5.3 hours sleep per night for 18 nights, showed no performance defi cits on logical reasoning or auditory vigilance, despite their reports of severe increases in subjective sleepiness and reduced concentratio n. Both these sleep reduction groups, though, did show decrements on t he FEFT, which we interpret in terms of dearousal increasing distracti bility, which the sleep-reduced subjects could not overcome with effor t, as they did with the other tests.