The first signs that a person is not getting enough sleep are when they are irritable, moody, frustrated and disoriented. According to psychologist and expert on sleep, David F. Dinges, Ph.D. of the Division of Sleep and Chronobiology and Department of Psychiatry at the University of Pennsylvania School of Medicine, if a person continues to not get enough sleep, he or she may develop a slowness to speech patterns, impaired memory, and flattened emotional responses. The individual can also become apathetic. This person's productivity levels will decline steadily and their ability to multitask at their job will drop sharply.