Functional neuroimaging in sleep, sleep deprivation, and sleep disorders

This chapter presents the neuroimaging studies conducted during normal sleep. The studies using positron emission tomography (PET), single photon emission computed tomography (SPECT) or functional magnetic resonance imaging (fMRI) is reviewed in the chapter. They show that global and regional patterns of brain activity during sleep are outstandingly different from wakefulness. These studies also demonstrated the persistence of brain responses to external stimuli during sleep as well as plastic changes in brain activity related to previous waking experience. The chapter discusses that brain functional imaging in patients affected by sleep disorders may address different kinds of issues. The first topic is the characterization of the cerebral aftermath of sleep disruption due to intrinsic sleep disorders or to extrinsic environmental or medical causes. The second, more ambitious aim would be to characterize better the primary physiopathological mechanisms of sleep disorders, or at least their cerebral correlates. This attempt is hampered by several factors described in the chapter.