Circadian Rhythms in Attention

Attention is a cognitive process crucial for human performance. It has four components: tonic alertness, phasic alertness, selective attention, and sustained attention. All the components of attention show homeostatic (time awake, sleep deprivation) and circadian (time of day) variations. The time course of the circadian rhythms in attention is important to program work and school-related activities. The components of attention reach their lowest levels during nighttime and early hours in the morning, better levels occur around noon, and even higher levels can be observed during afternoon and evening hours. However, this time course can be modulated by chronotype, sleep deprivation, age, or drugs. Homeostatic and circadian variations have also been found in other basic cognitive processes (working memory and executive functions), with a time course similar to that observed for attention. Data reviewed in this paper suggests the need to consider circadian rhythms, age, and chronotype of the person, when programming schedules for work, study, school start time, school testing, psychological testing, and neuropsychological assessment.