Such is the case for schizophrenia, depression, Parkinson’s disease (PD), and Alzheimer disease (AD), where patients display altered sleep, and melatonin and core body temperature rhythms, due to alterations in clock gene expression and the loss of synchronization among pacemaker cells in the SCN (Videnovic et al., 2014; Musiek and Holtzman, 2016). Here, CLOCK is linked to Alzheimer disease.