Per2 also known as FASPS is a member of the Period family of genes and is expressed in a circadian pattern in the suprachiasmatic nucleus, the primary circadian pacemaker in the mammalian brain. Per2 plays a crucial role in regulating circadian rhythms, which are essential for maintaining the body′s internal clock and synchronizing physiological processes with the day-night cycle. Located primarily in the suprachiasmatic nucleus (SCN) of the brain, Per2 is involved in the transcriptional feedback loop that regulates the expression of other clock genes, thereby influencing sleep-wake cycles, hormonal rhythms, and metabolic processes. Per2 interacts with other core clock proteins, such as Clock and BMAL1, to modulate their activity, and disruptions in Per2 function can lead to sleep disorders and metabolic syndromes.