Narcolepsy is a neurological disorder caused by a loss of hypocretin neurons in the lateral hypothalamus. This disorder is characterized by excessive sleepiness, sleep-wake instability, increased rapid eye movement (REM) sleep propensity and cataplexy. From a neurobiological perspective, sleep - in particular REM sleep and cataplexy - and thermoregulatory control are tightly integrated. This integration occurs in part within the hypothalamus. Current work from this ZEN group shows that ambient temperature warming significantly reduces cataplexy while increasing REM sleep without affecting waking, whereas cooling increases cataplexy and decreases REM sleep.