This chapter reviews the spectrum of neuroimaging in Kleine-Levin syndrome (KLS). Although structural neuroimaging in KLS is within the normal range in most cases, the vast majority of studies report hypoperfusion in several brain regions. Cognitive impairment and altered perception occur in all KLS patients during sleep episodes according to the review by Arnulf. It is thus pertinent to investigate the neural concomitants to cognitive function in KLS by functional neuroimaging. N-Acetylasparate (NAA) is a biomarker for neuronal health, associated with either neuronal loss or neuronal dysfunction. Hypothalamic pathology constitutes a main hypothesis for KLS etiology. This hypothesis is based on the important function of the hypothalmus in sleep and appetite regulation as well as regarding sexual activity. The sparsity of neuroimaging findings in the hypothalamus might be a result of the detection limit for functional imaging in this region of the brain.