the daily rhythms of locomotor activity, metabolism, and behavior. Circadian expression of these genes and their encoded proteins in the suprachiasmatic nucleus. Human PER2 is involved in human sleep disorders and cancer formation. Lowered PER2 expression is common in many tumors cells within the body, suggesting PER2 is integral for proper function and decreased levels promotes tumor progression.

PER2 contains glucocorticoid response elements (GREs) and a GRE within the core clock gene