First International School On Mind, Brain And Education

2005 July 16-20

Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, ARGENTINA

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Chronoeducation: interactions between the circadian system and learning processes
Many biological functions wax and wane in cycles that repeat each day, month, or year. Such patterns do not reflect simply organism's passive response to environmental changes. Rather, they reflect the organism's biological rhythms, that is, its ability to keep track of time and to direct changes in function accordingly. Circadian clock mechanisms involve periodic gene expression, synchronized by a hierarchically superior structure located in mammals in the hypothalamic suprachiasmatic nuclei. A very important general principle about the circadian system relevant to learning is that it adapts slowly to changes in sleep/wake schedules. Thus, adolescents who rapidly shift sleep/wake schedules between school nights and weekends or vacations can face circadian consequences. Another important general principle about the circadian timing system relevant to education is that the circadian system adapts more easily to delays in the sleep/wake schedule rather than to advances. This is why it is naturally easier to stay up later and sleep in later on weekends. Many adolescents have abrupt changes in the timing of their sleep between regular school schedules, requiring early morning awakening, and the late bedtimes, with quick shifts back to late bedtimes and sleeping in on weekends and vacations. Therefore, many adolescents may experience jet lag-like symptoms of fatigue, difficulty in falling asleep at night, and difficulty in awakening in the morning. An important association exists between the learning processes and sleep. Several studies have shown augmentation in sleep amounts or sleep architecture following learning tasks and disruption of sleep in the night following learning impairs the learning of the task. Since modern humans use artificial light to extend their period of wakefulness and activity into the evening hours, they adhere to a short night sleep schedule with a highly consolidated and efficient sleep. As shown by studies in artificial long nights as well as by epidemiological studies, modern humans may be sleep-deprived. In this presentation I will discuss the physiological consequences of such sleep deprivation with a focus in the learning processes.