CLOCK and mood disorder: Not surprisingly, a number of circadian clock DNA mutations are also associated with chronotype, sleep disturbance, and mood disorders (Archer et al., 2003; Partonen et al., 2007; Lavebratt et al., 2010a,b; Hida et al., 2014; Kim et al., 2015; Liu et al., 2015; Zhang et al., 2016).