This chapter reviews functional brain imaging studies conducted in narcoleptic patients. Several functional neuroimaging studies were conducted to evaluate the distribution of brain activity during wakefulness and sleep in narcolepsy. Three of them described CMRglu and rCBF patterns during resting wakefulness. Processing of emotional information potentially plays an important role in narcolepsy-cataplexy. Brain responses to unpleasant stimuli were investigated in nine unmedicated narcoleptic patients with cataplexy and nine matched controls. Anticipation of reward constitutes a particular emotional experience prone to trigger cataplexy in humans, which suggests a potential involvement of the hypocretin system in reward brain circuits, and possible alterations of these circuits in narcolepsy with cataplexy. In the narcolepsy group, significant positive correlations were found between disease duration and functional magnetic resonance imaging (fMRI) responses to high motivational cues in the nucleus accumbens and ventromedial prefrontal cortex.