The effects of low intensity 810 nm laser irradiation (LIDL) to the tumor necrosis factor (TNF)-α induced expression suppression of circadian clock genes in cultured NIH3T3 fibroblasts are investigated. The fibroblasts shocked by horse serum for 2 h are induced with TNF-α of 10 ng/mL, and then irradiated by different doses of LIDL once. The results show that TNF-α induced inhibition effect of the circadian clock gene expression can be modulated by LIDL, which may be mediated by nicotinamide adenine dinucleotide/ reduced form of nicotinamide adenine dinucleotid (NAD+/NADH) and sirtuin 1 (SIRT1).