Delta Sleep–Inducing Peptide (DSIP) is a naturally occurring neuropeptide that has attracted scientific interest for its potential role in sleep regulation, stress response, and neuroendocrine balance. Identified in early sleep research, DSIP is being explored for how it may influence circadian rhythms, hormone modulation, and central nervous system signaling pathways. Current peptide research focuses on DSIP’s interaction with brain activity associated with restorative sleep cycles, particularly its potential influence on delta-wave patterns. Investigators are also examining its broader physiological relevance, including adaptive stress response, cognitive recovery processes, and regulatory effects on key hormonal systems.