Another thing that your brain does while you sleep is process your emotions. Your mind needs this time in order to recognise and react the right way. When you cut that short, you tend to have more negative emotional reactions and fewer positive ones.
Sleep lets your brain catch up so you’re ready for what’s next.
While you sleep, your blood pressure goes down, giving your heart and blood vessels a bit of a rest. The less sleep you get, the longer your blood pressure stays up during a 24-hour cycle. High blood pressure can lead to heart disease, including stroke.
Short-term down time can have long-term payoffs.
Many studies have been done with the relation to weight because let us be honest, many people are more concerned with their weight than their sleep! The good news is that lack of sleep does increase your chances of obesity. The bad news is if you do not believe sleep is all that important, but your weight is, then you are not helping your weight problem by not getting the proper sleep (7-9 hours).
The reasoning for weight gain is the longer you are awake the hungrier you will become. Your body needs energy to keep going and if you are staying up long hours, the more energy it will require.