CLOCK and sleep disorder: Exposure to bacteria, virus, toxins, pesticides, stress, life styles changes, sleep disorders, etc, all (in combination or alone) affecting the circadian clock and increase vulnerability to head and neck pathologies (Hooven et al., 2009; LeGates et al., 2014; Cui et al., 2016; Potter et al., 2016; Koch et al., 2017; Kopp et al., 2017).