DANIEL BUYSSE, MD: Insomnia as difficulty sleeping during the night can occur at any point during the night really, although some people will have mainly difficulty falling asleep, other people will have mainly difficulties because of frequent awakenings during sleep. And in many cases, people will just have difficulty returning to sleep once they have awakened in the middle of the night.
ANNOUNCER: But what is a good night's sleep? The answer is different for everyone.
DANIEL BUYSSE, MD: The amount of sleep is not defined by a certain number of hours, because different people need different amounts of sleep. There are certainly short sleepers and there are long sleepers. But the thing that categorizes adequate sleep is that the person's able to remain awake and to function well during the day.
ANNOUNCER: Many sleep problems are temporary, usually caused by a particular event or poor sleep environment.
DANIEL BUYSSE, MD: Transient insomnia is defined as something that lasts less than two or three weeks. And it's usually a problem that occurs in the context of some other stress in the person's life. Whether it's a stress in terms of their life situation, problems at work, problems in their family or perhaps a stress in terms of a medical problem, an acute medical illness.
ANNOUNCER: Chronic or more persistent insomnia can result from several factors.
DANIEL BUYSSE, MD: Virtually every chronic medical illness can cause insomnia. Things that cause pain, things that impair our ability to move at night, things that cause difficulty breathing are common examples of medical conditions that may be associated with insomnia.