The importance of sleep for your overall health cannot be understated. However, just how many hours of sleep a person needs every day varies depending on his or her age, gender, genetics, activity level and other health factors. Sleep directly impacts your mental and physical health in significant ways. Sleep deprivation can generate mild symptoms such as tiredness, trouble concentrating or irritability, but over time, it can result in more significant health conditions such as mood disorders, high blood pressure, diabetes, obesity, stroke and various mental illnesses.