eMedicine Specialties > Pulmonology > Sleep-Related Disorders

Insomnia

Author: Peter Smethurst, MD, Attending Physician, Pulmonary, Critical Care and Sleep Medicine, St Joseph's Medical Center
Coauthor(s): Silverio M Santiago, MD, Clinical Professor of Medicine, University of California at Los Angeles School of Medicine; Chief, Department of Pulmonary and Critical Care Medicine, Medical Director, Sleep Disorders Center, Veterans Affairs Medical Center of West Los Angeles; James A Rowley, MD, Associate Professor, Fellowship Program Director, Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Wayne State University School of Medicine
Contributor Information and Disclosures

Updated: Jul 25, 2008

Introduction

Background

Insomnia is defined as difficulty with sleep initiation, maintenance, or quality despite adequate time and opportunity that occurs on a repeat basis and results in some form of daytime impairment. It is the most commonly reported sleep-related problem, with approximately 10-15% of Americans having daytime impairment as a result of the sleep disturbance, and is associated with a variety of medical, psychiatric, and sleep disorders. A comprehensive history and physical examination is essential for determining the underlying etiology of insomnia.

A patient's report of insomnia is nonspecific and can encompass a variety of concerns, including difficulty falling asleep, awakening early or easily, problems with returning to sleep after awakening, or a general poor quality of sleep. Therefore, the patient must define what he or she means by insomnia. In order to be considered a disorder, the insomnia should be accompanied by daytime sleepiness, loss of concentration, irritability, worries about sleep, loss of motivation, or other evidence of daytime impairment that is associated with the sleep difficulty.

Insomnia is commonly divided into 3 types based on duration. The first type is transient insomnia. Transient insomnia lasts up to 1 week and is often referred to as adjustment sleep disorder because it is caused most often by an acute situational stress, such as a new job, upcoming deadline, or examination. It is often recurrent with new or similar stresses. The second type, short-term insomnia, is defined as that lasting 1-6 months and is usually associated with more persistent stressful situational (death or illness) or environmental (noise) factors. The third type is chronic insomnia. Chronic insomnia is any insomnia lasting more than 6 months and is associated with a wide variety of disorders.

Other related eMedicine articles include Insomnia (neurology focus) and Primary Insomnia. In addition, the following Medscape CME courses are available:

• Insomnia: Impact on Health and Quality of Life
• Insomnia and Comorbid Anxiety
• The Treatment of Insomnia in Older Adults

Pathophysiology

Determinants of insomnia

Insomnia is usually a result of an interaction of biological, physical, psychological, and environmental factors.

While transient insomnia can occur in any person, chronic insomnia appears to develop only in a subset of patients who may have predisposing factors. The evidence supporting this theory indicates that, compared with persons who have normal sleep, persons with insomnia (1) have higher rates of depression and anxiety, (2) score higher on scales of arousal, (3) have longer daytime sleep latency, (4) have increased 24-hour metabolic rates,¹ (5) have more night-to-night variability in their sleep, and (6) may have more beta electroencephalogram activity (a pattern observed during memory processing/performing tasks) at sleep onset.

In experimental models of insomnia, normal subjects deprived of sleep do not demonstrate the same abnormalities in metabolism, daytime sleepiness, and personality as subjects with insomnia. In an experimental model in which normal subjects were given caffeine, causing a state of hyperarousal, the normal subjects had changes in metabolism, daytime sleepiness, and personality similar to subjects with insomnia.² These results support a theory that insomnia is a manifestation of hyperarousal. In other words, the poor sleep itself may not be the cause of the daytime dysfunction, but merely the nocturnal manifestation of a general disorder of hyperarousability.

One theory holds that chronic insomnia is the result of 3 components: predisposing factors, precipitating factors, and perpetuating factors. Patients who develop chronic insomnia are thought to have predisposing factors that put them at risk. These factors may cause the occasional night of poor sleep, but, in general, the patient sleeps well until a precipitating event (eg, death or other life stress) occurs. Then, the patient develops acute insomnia. If the patient develops bad sleep habits or other perpetuating factors, chronic insomnia develops despite the removal of the precipitating factor. This theory is illustrated in Media File 1.

Frequency

United States

In a 1991 survey, 30-35% of adult Americans reported difficulty sleeping in the past year and 10% reported the insomnia to be chronic, severe, or both. Despite the high prevalence, only 5% of individuals with chronic insomnia visited a clinician specifically to discuss their insomnia, while only 26% discussed their insomnia during a visit made for another problem.

International

A study from Quebec indicated an overall prevalence rate of insomnia of approximately 20% in French Canadians. A study of young adults in Switzerland indicated a 9% rate of chronic insomnia. A World Health Organization study of 15 sites found a prevalence rate of approximately 27% for patients reporting "difficulty sleeping."

Mortality/Morbidity

• Individuals with insomnia report an impaired ability to concentrate, poor memory, difficulty coping with minor irritations, and decreased ability to enjoy family and social relationships.
• Individuals with insomnia are more than twice as likely to have a fatigue-related motor vehicle accident.
• The mortality rate appears to be higher in patients who sleep fewer than 5 hours each night.

Sex

The prevalence rate of reported insomnia is higher in women than in men (approximately 40% vs 30%).

Age

Frequency increases with age.

Clinical

History

The history is the most important part of the evaluation for insomnia. It must include a complete sleep history, medical history, social history, and careful medication review.

• Sleep history
  • As part of the sleep history, the examiner must determine the timing of insomnia, the patient's sleep habits (commonly referred to as sleep hygiene), and the symptoms of the sleep disorders associated with insomnia.
  • To determine the timing of insomnia, several types of questions should be asked. At what time is the sleep difficulty occurring? Is the difficulty with falling asleep, frequent awakenings, or early morning awakening? If the problem is at sleep onset, is the patient sleepy when he or she gets into bed?
  • Try to determine the patient's sleep schedule. What time does the patient go to bed and wake up in the morning? Do these occur at the same times every day? Have any recent changes occurred in this schedule? Does the patient take daytime naps?
  • Inquire about the patient's sleep environment. What are the temperature, bed comfort, and noise and light levels? Does the patient sleep in his or her own bed? Does the patient sleep better in a chair or when away from home (eg, hotel)?
  • Sleep habits can also be determined with questioning. Individuals with insomnia often have poor sleep hygiene. Does a period of relaxation occur prior to bedtime or does the patient work until bedtime? Does the patient read or watch television in bed? Is the television or a light kept on during the night? What does the patient do if he or she cannot fall asleep? If he or she wakes up in the middle of the night, does the patient fall back to sleep easily? If not, what does the patient do? Does the patient take daytime naps? Does the patient exercise and when?
  • Symptoms of other sleep disorders should be elicited. Symptoms of obstructive sleep apnea include snoring, witnessed apneas, and gasping. Symptoms of restless legs syndrome (RLS) or periodic limb movement disorder (PLMD) include a restless feeling in the legs upon lying down that improves with movement, rhythmic kicking during the night, and very crumpled or disrupted sheets in the morning.
• Daytime history
  • Daytime effects should be present if the patient is truly not sleeping at night. In fact, if no daytime effects are present, the patient is likely getting adequate sleep and the report of insomnia is truly subjective.
  • Common symptoms include fatigue, tiredness, lack of energy, irritability, reduced work performance, and difficulty concentrating.
  • These should be distinguished from reports of excessive sleepiness, which is rare in persons with insomnia.
• Medical history: Perform a thorough medical history and review of systems, with particular emphasis for those disorders mentioned in Causes.
• Psychiatric history: Perform a thorough psychological review to screen for a psychiatric disorder (see Causes).
• Social history
  • For adjustment (also known as transient, short-term, or acute) insomnia, inquire about recent situational stresses such as a change in job/school or bereavement.
  • For chronic insomnia, attempt to relate the onset of insomnia to past stresses or medical illnesses.
  • Perform a thorough history of the use of tobacco, caffeinated products, alcohol, and illegal drugs.
• Medication history: Medications that commonly cause insomnia include beta-blockers, clonidine, theophylline (acutely), certain antidepressants (eg, protriptyline, fluoxetine), decongestants, and stimulants.

Physical

The physical examination may be helpful in the evaluation because findings may offer clues to underlying medical disorders predisposing the patient to insomnia.

• If the patient reports sleep apnea, perform a careful head and neck examination. Common anatomic features associated with sleep apnea include lateral narrowing of the oropharynx, oropharyngeal crowding secondary to increased tongue and soft tissue volume, enlarged tonsils, micrognathia, and retrognathia.
• If the patient reports symptoms of RLS or any other neurologic syndrome, perform a careful neurologic examination.
• If the patient reports daytime symptoms consistent with any of the medical causes of insomnia listed below, a careful examination of the affected organ system (eg, lungs in chronic obstructive pulmonary disease) may be helpful.

Causes

• Adjustment insomnia (also known as transient, short-term, or acute insomnia): Etiologies for these disorders can be divided into 2 broad categories.
  • Environmental etiologies result from an unfamiliar or nonconducive sleep environment due to factors such as too much noise or light, extremes of temperature, or an uncomfortable bed or mattress.
  • Stress-related etiologies primarily result from life events such as new job or school, deadlines or examinations, or deaths of relatives and close friends.
• Chronic insomnia: The differential diagnosis is broader and includes the categories below.
  • Medical disorders may include chronic pain syndromes from any cause (eg, arthritis, cancer), advanced chronic obstructive lung disease, chronic renal disease (especially if on hemodialysis), chronic fatigue syndrome, and fibromyalgia.
  • Neurologic disorders may include Parkinson disease, other movement disorders, and headache syndromes, particularly cluster headaches, which may be triggered by sleep.
  • Most chronic psychiatric disorders are associated with sleep disturbances.
    • Depression is most commonly associated with early morning awakenings and an inability to fall back asleep; studies have also demonstrated that insomnia can lead to depression. Insomnia of more than 1-year duration is associated with an increased risk of depression.
    • Schizophrenia and the manic phase of bipolar illness are frequently associated with sleep-onset insomnia.
    • Anxiety disorders (including nocturnal panic disorder and posttraumatic stress disorder) are associated with both sleep-onset and sleep-maintenance complaints.
• Drug-related insomnia: Sleep disruption is common with the excessive use of stimulants, alcohol, or sedative-hypnotics. The sleep disturbance may be related to periods of use or discontinuation of the substance or substances.
• Primary sleep disorders
  • RLS and PLMD: RLS is a sleep disorder characterized by unpleasant physical sensations in the legs; relief of the symptoms with movement; worsening of the symptoms during periods of rest or inactivity; and the presence of symptoms primarily in the evening and at night. RLS may be associated with PLMD (repetitive periodic leg movements that occur while asleep). If RLS is predominant, sleep-onset insomnia is generally present; if PLMD is predominant, sleep-maintenance insomnia is more likely.
  • In obstructive sleep apnea, a small subset of patients report insomnia rather than hypersomnolence. They frequently report multiple awakenings or sleep-maintenance difficulties.
  • Circadian rhythm disorders may include advanced sleep-phase syndrome (patient goes to bed early and rises early) and delayed sleep-phase syndrome (patient goes to bed late and rises late). They can manifest as insomnia when the patient wants to either stay in bed later or go to bed earlier but cannot and then believes he or she has a problem sleeping. Shift workers also frequently have problems with insomnia, particularly when required to sleep during the day.
• Psychophysiological insomnia: This is a disorder of somatized tension and learned sleep-preventing associations resulting in a complaint of insomnia and daytime fatigue.
  • Insomnia begins with a prolonged period of stress in a person with previously adequate sleep. The patient responds to stress with somatized tension and agitation, causing physiologic arousal. The bedroom routine, sleep routine, or both become associated with frustration and arousal; poor sleep hygiene follows.
  • In a person experiencing normal sleep, as the initial stress abates, the bad sleep habits are gradually extinguished because they are not reinforced nightly. However, in a patient with a tendency toward occasional poor nights of sleep, the bad habits are reinforced, the patient "learns" to worry about his or her sleep, and chronic insomnia follows.
  • History in these patients frequently reveals excessive daily worries about not being able to fall asleep. They have difficulty falling asleep at bedtime, but they may fall asleep unintentionally during monotonous pursuits (eg, watching television, reading) or in inappropriate situations (eg, at a lecture, while driving) but not when desired. The patient may sleep better when outside of his or her usual sleep environment (eg, away from home). The patient may also report increased arousal, agitation, and muscle tension at or prior to bedtime.
• Infrequent causes: Rarely, insomnia is caused by idiopathic insomnia (long-standing insomnia beginning in childhood without antecedent psychiatric or medical cause) or paradoxical insomnia, a sleep-state misperception for which the patient reports insomnia but does not have objective evidence of a sleep disorder.

• Search for CME/CE on This Topic »

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