The neuropsychological investigation of sleep: practical and methodological aspects.

Some stimulating areas in the field of neuropsychological research on sleep-wake behaviour are presented in this introductory paper using recent publications by eminent researchers. In the first part the cerebral asymmetry theory proposed by Ornstein is presented. Do the rhythmic oscillations of the sleeping brain go together with different forms of cognitive information processing? In the second part the work of some Italian researchers on dreaming experience in neurological patients is presented and commented. At a moment when the emphasis in sleep research is on medical-biological aspects, psychologists are challenged to produce some creative ideas in the field of neurocognition of sleep-wake behaviour.