Not enough sleep...
Sleep deprivation occurs when an individual fails to get enough sleep. Our ability to function and feel well while you're awake depends on whether you're getting enough total sleep and enough of each type of sleep. A common myth is that people can learn to get by on little sleep with no negative effects. However, research shows that getting enough quality sleep at the right times is vital for mental health, physical health, quality of life, and safety.
...causes serious health problems...
Skipping sleep has been linked to less-threatening problems -- like a headache -- and even life-threatening ones and earlier death. People do not realize is that a lack of sleep—especially on a regular basis—is associated with long-term health consequences, including chronic medical conditions like diabetes, high blood pressure, and heart disease, and that these conditions lead to a shortened life expectancy.
Sleep deficiency also is associated with an increased risk of injury in adults, teens, and children. For example, driver sleepiness (not related to alcohol) is responsible for serious car crash injuries and death. In addition, sleep deficiency has played a role in human errors linked to tragic accidents, such as nuclear reactor meltdowns, grounding of large ships, and aviation accidents.