We all know that getting a good night’s sleep is important, but just how important is it? Well, according to Dr. David F. Dinges of the Division of Sleep and Chronobiology and Department of Psychiatry at the University of Pennsylvania School of Medicine, the first signs of lack of sleep are irritability and moodiness. If the person continues to not get enough rest, they will eventually start to experience apathy, slowed speech and flattened emotional responses, impaired memory, and an inability to be novel or to multitask. If you still do not take notice and get some shut eye, then what comes next can be physically disastrous.