Fig 2.
Hypocretin system. The sleep-wake cycle is governed by a complex, multilevel neuronal system in the brain stem, thalamus, hypothalamus, and basal forebrain. Neurones in the hypothalamus producing hypocretin stabilise the activity of other key neuronal groups involved in the control of sleep and waking: these nuclei and their principal neurotransmitters are shown here in highly schematic fashion