Functions as a suppressor of the biological clock that drives the daily circadian rhythms of cells throughout the body (PubMed:25936801). Acts as a nuclear repressor of the CLOCK-BMAL1 heterodimer-mediated transcriptional activation of the core clock components (PubMed:25936801). Inhibits circadian clock function in cancer cells, when overexpressed (PubMed:25936801). . This is the function of ENSG00000166049 (PASD1, PAS domain containing repressor 1).