A circadian system model with feedback of cross-correlation between sleep-wake rhythm and oscillator

Recent findings suggest that social entrainment factors work on an oscillator other than the temperature and melatonin rhythms. This indicates that there is a feedback loop affected on oscillators. In the present study, a circadian system model, including mutually coupled two oscillators and sleep-wake rhythm, is constructed, where cross-correlation between a sleep-wake rhythm and an oscillator is set to modify the coupling from one oscillator to the other. Based on the model simulation, a mechanism underlying delayed sleep phase syndrome is elucidated by the reduction in the cross-correlation resulting from dissociation between the delayed sleep phase and the oscillator.