Why is sleep so important?
During sleep, your body temperature and blood pressure drop, your heart rate decreases, your breathing becomes slower, and your muscles are relaxed - to put it briefly, your body regenerates.
Without these recovery periods, human beings wouldn't survive. During night sleep, cells regenerate faster and the body refills energy reserves. Moreover, your immune system is strengthened and your hormones are naturally balanced. Therefore, sleep is very important for being generally fit and healthy.