Studies show that there is a strong correlation between sleep and certain diseases. A lack of sleep can play a role in diabetes, cardiovascular disease, obesity, and depression. Sleep duration can predict levels of hemoglobin A1c which is responsible of blood sugar control. Common physiological characteristics are seen between sleep apnea and atherosclerosis, causing the correlation between sleep and cardiovascular disease. Interestingly, sleep plays a role in brain development, in result insufficient sleep can affect parts of the brain that control appetite and depression. For more information check out www.cdc.gov.