CLOCK and intervertebral disk degenerative disorder: The IVD is a highly rhythmic tissue that experiences a diurnal activity/rest cycle.26,27 Shift work, which disrupts the diurnal rhythmic cycle, is considered a risk factor for LBP.28,29 Previously, our group showed that IVDs contain an intrinsic circadian clock, which could be regulated by aging and disrupted by IL-1β.30 However, the effect of abnormal mechanical loading on the IVD circadian clock and the role it plays in IDD development and progression have not been explored.