Weight gain - When you're sleep-deprived, your body increases the hormone that tells you you're hungry and decreases the hormone that controls your appetite. Sleep deprivation also increases cravings for foods high in fat and simple carbohydrates — in other words, junk food.
Heart disease - Chronic sleep deprivation can have negative effects on the body's ability to regulate cortisol. Increased levels of cortisol lead to increased blood pressure, which can lead to a number of problems, including an elevated risk for heart disease, the leading cause of death for men and women in the U.S.
Diabetes - With the chronic loss of sleep, less insulin is released into the body after meals. This results in too much glucose in the bloodstream, which is the signal for type 2 diabetes. Your risk for type 2 diabetes nearly triples with chronic sleep deprivation.
Lowered immunity - Without sufficient sleep, the body makes fewer cytokines, which are a type of protein that target infection and inflammation, supporting the body's immune response.
Premature aging of the skin - Everyone knows that a lack of sleep can cause dark circles under the eyes. But something more insidious is going on with persistent sleep deprivation. The release of cortisol that accompanies chronic sleep deprivation breaks down collagen, the protein that allows the skin to stretch and expand while maintaining youthful smoothness. Without collagen, skin becomes loose and wrinkled.
Poor judgment - Basically, a lack of sleep makes you stupid. Without proper sleep, the brain is unable to process what we've learned and we have more trouble remembering it later when we need it. Mental alertness and cognitive function go way down.
Irritability, anxiety, and depression - Over time, a lack of sleep can contribute to the symptoms of depression. Returning to normal sleep may reduce these symptoms almost immediately.