Clinical trial: imaging techniques in sleep studies

Sleep is a global phenomenon affecting the whole brain and in which the brain activity dynamically changes across the stages. Sophisticated imaging techniques have been developed to investigate the intriguing interaction: sleep-brain. This chapter critically reviews the main applications of imaging studies in the field of sleep research. The neural correlates of sleep stages, in particular nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep as well as the phasic activity characterizing these stages will be discussed with magnifying glass focus on neuroimaging. Functional neuroimaging studies disrupted the basic neurophysiological notions on sleep, demonstrating that brain activity is increased during NREM sleep in synchrony to specific phasic NREM oscillations. As well as REM sleep may be characterized by cortical deactivation/quiescence especially the prefrontal cortex. The clinical relevance of this evidence consists for improving the knowledge on mechanisms and neural networks underlying the physiology of the human sleep.