Lack of rest slows activity in the prefrontal cortex, the part of the brain responsible for decision-making and impulse control. At the same time, the brain’s reward system becomes more sensitive to pleasurable stimuli. This combination makes it harder to stay focused and easier to reach for convenient comforts such as caffeine, sweets or scrolling.
Your circadian rhythm is your body’s natural 24-hour clock. It helps control when you feel awake and when you feel sleepy. It also affects your hunger, mood, energy and even how your body uses food.