In the lungs of mice exposed to cigarette smoke, altered rhythms of SIRT-1 protein and core clock genes including Bmal1, Clock, Per1, Per2, Cry1, Cry2, Nr1d1, Nr1d2, and Rora were observed in a circadian manner, increasing the susceptibility to inflammation and emphysema development (58). Here, CLOCK is linked to pulmonary emphysema.