Connecting the circadian (SCN), mood (DRN), and reward (VTA, NAc) systems. Note the solid lines represent direct connections, and the dashed lines represent indirect connections. SCN = suprachiasmatic nucleus, DRN = dorsal raphe nucleus, VTA = ventral tegmental area, and NAc = nucleus accumbens. Listed are the following direct connections: DRN to SCN (Kiyasova et al., 2011; Paulus and Mintz, 2012), DRN to VTA (Vertes and Linley, 2007), DRN to NAc (Vertes and Linley, 2007), VTA to SCN (Grippo et al., 2017), VTA to DRN (Kirouac et al., 2004), VTA to NAc (Russo and Nestler, 2013), and NAc to VTA (Russo and Nestler, 2013). Listed are the following indirect connections: SCN to DRN (Deurveilher and Semba, 2008) and SCN to VTA (Luo and Aston-Jones, 2009).