Pathways involved in the hypothalamic control of the circadian rhythms of sleep, wakefulness and body temperature. In the regulation of circadian sleep-wake patterns, outputs from the SCN relay at the vSPZ, and project to the DMH. The DMH then sends outputs to the VLPO (a sleep-activating center), and the LHA (where orexin neurons target downstream wake-promoting sites). The SCN regulates circadian body temperature rhythms through a relay at the dSPZ, which projects to the MPO. SCN, suprachiasmatic nucleus; vSPZ: ventral subparaventricular zone; dSPZ: dorsal subparaventricular zone; DMH: dorsomedial nucleus; VLPO: ventrolateral preoptic nucleus; LHA: lateral hypothalamic area; MPO: medial preoptic nucleus; MCH: melanin-concentrating hormone; TRH: thyrotropin-releasing hormone. Modified with permission from [9].