They don't call it "beauty sleep" for no reason

Without the sleep you need, you’ll look older and your skin will look drier. Your skin renews itself as you sleep which is why too little sleep can make your skin look tired and dull. Sleep renews and refreshes us and is vital for good health and beauty. The average need for an individual is eight hours; it varies from person to person. Identify your need by the way you feel when you wake up.

Self discipline is required to get required amount of sleep. Even than it is not always possible to get that but do be sure that you’re not regularly losing out on sleep. Never reach the awful stage where you feel incredibly tired and your body cries out for sleep.