INSOMNIA

Sleep Disorders

Clinical classifications of insomnia and its host of conditions and causes are extensive and specific. The spectrum of causes suggests that it is difficult to obtain good sleep and that sleep is, in fact, a delicate environment, the path toward which may be strewn with obstacles.

Insomnia is not a disease; rather, it is a complex symptom that results from insufficient sleep or sleep of poor quality. However, insomnia is distinguishable from short sleep. Many people sleep less than 75% of conventional eight-hour sleep time and experience no difficulty sleeping or waking. Insomnia is divided generally into two main categories: sleep onset insomnia and sleep maintenance insomnia. Sleep onset insomnia is the inability to fall asleep naturally. Sleep maintenance insomnia is the inability to stay asleep or to resume sleep after waking in the middle of the sleep cycle. A person may experience both sleep onset insomnia and sleep maintenance insomnia, which leads to both insufficient and poor sleep.

Insomnia can be categorized further as acute or chronic. Acute insomnia is self-limiting, meaning it runs its course in a few weeks or months and ends without being treated. Chronic insomnia lasts longer than three months and often needs to be treated. Insomnia can be caused by medical problems, such as chronic pain syndromes; psychiatric problems, such as depression; or primary sleep problems, such as periodic limb movement disorder (PLMD).

INCIDENCE

The prevalence of insomnia is unknown. Surveys of the general population suggest that 49% of adults report having brief periods of difficulty sleeping. About 10% of adults claim they have had insomnia lasting two weeks or longer, and, usually, about one-half of those who claim to have periods of difficult sleep also claim it is a significant problem in their lives. Since insomnia is frequently a symptom of illness, severe stress, trauma, and so on, its incidence varies with regard to age, sex, and severity of the predisposing condition.

There numerous causes of insomnia that can generally be broken down into three categories: (1) insomnia due to another sleep disorder, (2) insomnia due primarily to physical medical disorder, and (3) insomnia due primarily to psychiatric disorder.

CAUSES

Insomnia Due to Sleep Disorders

Psychophysiological Insomnia, Difficulty Initiating and Maintaining Sleep (DIMS
Sleep State Misperception
Obstructive Sleep Apnea (OSA)
Central Sleep Apnea (CSA)
Sleep Hygiene and Environmental Sleep Disorder
Altitude Insomnia
Adjustment Sleep Disorder
Limit-Setting Sleep Disorder
Sleep-Onset Association Disorder
Food Allergy Insomnia
Medication-Dependent Sleep Disorder
Stimulant-Dependent Sleep Disorder
Alcohol-Dependent Sleep Disorder
Toxin-Induced Sleep Disorder
Time-Zone Change (Jet Lag)Syndrome
Shift Work Change Sleep Disorder (SWC)
Irregular Sleep-Wake Pattern
Delayed Sleep-Phase Syndrome (DSPS)
Advanced Sleep-Phase Syndrome
Non-24-Hour Sleep-Wake Syndrome
Nocturnal Leg Cramps

Psychophysiological Insomnia, Difficulty Initiating and Maintaining Sleep (DIMS)

The term psychophysiological describes the connection between the body (physiological) and the mind (psychological). People with psychophysiological insomnia have difficulty sleeping because they react to stress or physical illness with increased physiological arousal. This usually happens when a person does not resolve the stress-inducing factor in his or her life. Psychophysiological insomnia is caused by somatized tension, or stress that is expressed in bodily dysfunction, and learned associations that prevent sleep. Consequently, sleep, the one environment that soothes and rebuilds the body, is undermined by stress and anxiety. Eventually the activities and the environment associated with sleep - brushing one's teeth, turning off the light, lying still in bed - displace the original stress factor and lead to insomnia. Sleep onset insomnia or sleep maintenance insomnia may last years. People who associate anxiety with their conventional sleep environment typically find it easier to sleep in unfamiliar environments, such as a hotel room, a friend’s house, or the couch, where sleep-preventive associations are absent.

Sleep-State Misperception

People with sleep-state misperception sleep adequately but feel they do not. A disparity exists between the person’s subjective description of a night’s sleep and the objective measurement of the same night obtained in a sleep clinic. When asked about sleep, these people underestimate their total sleep time and overestimate the time it took them to fall asleep. Physicians speculate that this discrepancy results from an unclear perception of consciousness and difficulty distinguishing sleep from waking. During clinical testing, these sleepers often claim to have slept as little as one-half of the time that the polysomnogram readings indicate.