Effects of cumulative sleep loss and two nights' recovery sleep on multiple-task performance

The present study investigated the effects of five days' cumulative sleep restriction and two nights' recovery sleep on multiple-task performance and subjective sleepiness in a controlled laboratory environment. A total of 21 volunteers participated, thirteen in the experimental group and eight in the control group. Compared to the control group, the sleepiness of the sleep-loss group gradually increased over the five days, but returned to the baseline level after an eight hour recovery sleep period. Multiple-task performance declined selectively in the memory, arithmetic and auditory subtasks, while visual monitoring results were not affected. After the eight hour recovery period, the performance of the sleep-restricted participants in the auditory subtask remained low, although the individuals themselves no longer reported sleepiness. Performance in the rest of the tasks returned to the baseline level. Thus the partial cumulative sleep loss selectively impaired cognitive performance in subtasks of a multiple-task environment, which simulated many ordinary working environments. This may be due to the slowing of the cognitive processing during sleep restriction, as well as decline in attention control.