Schematic of neuronal wake-promoting populations. BF, basal forebrain; DA, dopamine; DR, dorsal raphe; Hcrt, hypocretin; His, histamine; LC, locus coeruleus; LH, lateral hypothalamus; NA, noradrenaline; PB, parabrachial area; PPT/LDT, pedunculopontine and laterodorsal tegmental nuclei; TMN, tuberomammillary nucleus; VTA, ventral tegmental area.