Staying up late for long periods of time can cause dizziness, memory loss, lack of concentration and slow reactions. And lack of sleep causes damage to the brain, something that cannot be repaired by catching up on sleep. Once normal sleep patterns are consistently disrupted, permanent damage is caused to the body’s organs and tissues, leading to a wide range of diseases. In extreme cases, sleep deprivation can lead to sudden death.
Studies have found that sleep between 6.5 and 7.5 hours has the lowest mortality rate; less than 6.5 hours increases the mortality rate, and especially less than 4.5 hours of sleep doubles the risk of death.