CLOCK and nervous system disorder: It is noteworthy that, in relation with microglia cells, it has been reported that abnormal microglia has a significant association with neurological disorders (Saijo and Glass, 2011; Louboutin and Strayer, 2013; Nakagawa and Chiba, 2015), and dysfunction of the clock system is one of the risk factors for the psychiatric diseases; therefore, the microglia clock may provide valuable targets for the development of novel therapeutic agent for the neurological disorders, and further research on this topic will aid in understanding the function and dysfunction of the brain.