In recent years sleep rhythm or chronotype have become one of the most studied subjects especially in psychology and educational environments. Chronotype is an important variable in interpersonal differences and it is related to psychological and physiological differences among people. There are three main chronotypes or eveningness, morningness…

Sleep deprivation adversely affects the ability to perform cognitive tasks, but theories range from predicting an overall decline in cognitive functioning because of reduced stability in attentional networks to specific deficits in various cognitive domains or processes. We measured the effects of sleep deprivation on two memory tasks, item…

Decades of research have established that "online" cognitive processes, which operate during conscious encoding and retrieval of information, contribute substantially to individual differences in memory. Furthermore, it is widely accepted that "offline" processes during sleep also contribute to memory performance. However, the question of whether…

The course of study of time-of-day effects on human performance has not been an easy one to chart, with many findings that seem to be in opposition. This review examines the difference between group and individual differences with regard to time-of-day effects; time-of-day effects in individuals; morningness-eveningness as an individual…