Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Insomnia is defined as difficulty initiating or maintaining sleep, or both, despite adequate opportunity and time to sleep, leading to impaired daytime functioning. Insomnia may be a cause of or result of poor quality and/or quantity of sleep.
Insomnia is very common. Ninety percent of the general population has experienced acute insomnia at least once. Approximately 10% of the population may suffer from chronic (long-standing) insomnia.
Insomnia affects people of all ages including children, although it is more common in adults and its frequency increases with age. In general, women are affected more frequently than men.
Insomnia may be divided into three classes based on the duration of symptoms.
Insomnia lasting one week or less may be termed transient insomnia;
short-term insomnia lasts more than one week but resolves in less than three weeks; and
long-term or chronic insomnia lasts more than three weeks.
Insomnia can also be classified based on the underlying reasons for insomnia such as sleep hygiene, medical conditions, sleep disorders, stress factors, and so on.
It is important to make a distinction between insomnia and other similar terminology; short duration sleep and sleep deprivation.
Short duration sleep may be normal in some individuals who may require less time for sleep without feeling daytime impairment, the central symptom in the definition of insomnia.
In insomnia, adequate time and opportunity for sleep is available, whereas in sleep deprivation, lack of sleep is due to lack of opportunity or time to sleep because of voluntary or intentional avoidance of sleep.
Insomnia is the perception of inadequate or poor-quality sleep. It can be due to problems falling asleep, early wakening, waking frequently during the night, unrefreshing sleep, or a combination of these. Contrary to some popular beliefs, insomnia is not defined by the total amount of sleep one gets or how long it takes a person to fall asleep. Individuals can vary in their need for sleep, and in the time required to fall asleep. What is a refreshing night's sleep for one person might be insomnia for another person.