Insomnia can be defined as the subjective complaint of impairment in the duration,
depth, or restful quality of sleep. It is characterized by one or more of the following problems:
difficulty falling asleep, difficulty maintaining sleep, early morning wakening, and unrefreshing sleep. Approximately 35 percent of the adult population have insomnia during the course of a year. Up to seven percent indicate the insomnia is chronic, severe, or both.In contrast to the
occasional sleepless night experienced by most people, insomnia may be a persistent or recurrent
problem with serious complications such as anxiety and depression.