With deep sleep, the energy lost during wakefulness is replenished, cell regeneration occurs, immunity is strengthened, stress and other negative sassm.org for kids factors occur, muscles are restored, blood pressure normalizes, and the pulse thins. The production of "stress" hormones (cortisol, adrenaline) decreases and the production of anabolic ones - testosterone, growth hormone increases. At rest, slow and coordinated work takes place, and the consciousness and subconsciousness also undergo purification and restoration.