In rabbit infused with δ-Sleep Inducing Peptide (DSIP), the spindle activity is increased, and heart and respiration rate are moderately decreased. δ-Sleep Inducing Peptide (DSIP) may act as a programming modulator at supra-operational level rather than as a transmitter at operational level. δ-Sleep Inducing Peptide (DSIP; 40 μg/kg, i.p.) increases catalase and superoxide dismutase (SOD) activities and malonic dialdehyde (MDA) concentration in the liver homogenate of rats subjected to acute stress, but the opposite effects are observed at 120, and 360 μg/kg.