The melatonin receptor Mtnr1a is differentially expressed in the hypothalamus and has links with circadian rhythms and also with exhaustion in shift workers (Sulkava et al., 2017), insomnia in schizophrenics (Park et al., 2011), and with Alzheimer’s (Sulkava et al., 2018). Here, MTNR1A is linked to insomnia.