How well you sleep at night directly impacts your mental and physical health and how you think, feel, and behave during the day. Sleep impacts your productivity and creativity at work or school, helps maintain your emotional balance, and affects your heart and brain health, your immune system, and even your weight. While you sleep, your body repairs tissue and your brain processes information and removes cellular waste. On the flip side, a lack of sleep can increase your risk of serious health conditions, such as high blood pressure, heart disease, stroke, anxiety, and depression.