Insomnia

I. Background
Insomnia is defined as a persistent difficulty initiating and/or maintaining sleep(1). Insomnia can be a primary syndrome; however, insomnia is more commonly a secondary symptom to underlying environmental, medical, or psychiatric disorders.
II. Pathophysiology
A. Etiology
Insomnia is caused by intrinsic disorders of the sleep-wake cycle and extrinsic factors affecting the quality or the timing of sleep. Depression, anxiety, and trauma can trigger insomnia, and over the years a perpetual cycle of poor sleep can continue even after the trigger is treated or removed (psychophysiological insomnia)(2). Poor sleep hygiene, a disruptive sleep environment, alcohol-dependence, and chronic use of hypnotics can also cause insomnia (2). Circadian rhythm disturbances (misalignment of sleep patterns with local time)(1) can present with the primary symptom of insomnia. Finally, many medical and psychiatric disorders can cause or be associated with insomnia.
B. Epidemiology
As many as 33% of the general adult population report symptoms of insomnia, and between 9% and 21% report insomnia with serious daytime consequences (3). Insomnia is more prevalent in women and increases in prevalence with increasing age (4).
III. Evaluation
A. History
A thorough history should focus on determining the cause and duration of insomnia. Precipitating events such as emotional trauma, illness, stress, and prescription or other drug use should be explored with the patient and his or her bed partner.
  • Sleep patterns A thorough discussion of the patient's sleep pattern and the sleep patterns of other members of their household should include the timing and the content of evening meals, bedroom environment (temperature, noise, comfort of bed), work schedules, and sleep schedules (including daytime napping).
  • Review of systems The review of systems should pay special attention to common medical and psychologic problems that are associated with insomnia.
  • Medications Table 2.9.1 lists medications that can cause insomnia.
B. Physical examination
The physical examination should focus on associated medical conditions associated with insomnia. In primary insomnia, the physical examination is likely to be normal.
C. Testing
Laboratory and diagnostic testing is infrequently useful in the diagnosis of primary insomnia. Asking the patient to keep a 7 to 14 day sleep diary may help in determining extrinsic factors causing insomnia (4,5). Polysomnography can assist in the diagnosis of some sleep disorders, including sleep apnea, restless leg syndrome and periodic limb movement disorder.
D. Genetics
Fatal familial insomnia is a rare prion disease that tends to run in families. In general, insomnia is not assumed to be genetically inherited (2).
IV. Diagnosis
A. Differential diagnosis (see Table 2.9.2)
The differential diagnosis of insomnia includes primary sleep disorders as well as medical, psychiatric, and environmental disturbances.
B. Clinical manifestations
Insomnia can cause significant functional impairment, difficulty in work or school, and marital or relationship problems. Chronic sleep loss from untreated insomnia can cause fatigue-related accidents at work or while driving, job loss, decreased productivity, major depression, and suicidal ideation (3). Individuals with insomnia may present with generalized fatigue or daytime sleepiness, and a careful history can help elucidate possible underlying problems of insomnia.
TABLE 2.9.1 Drugs that Cause Insomnia
Prescription drugs Nonprescription drugs
Methylphenidate Caffeine
Theophylline Stimulant diet pills
Albuterol Nicotine
Quinidine Illicit drugs (e.g., cocaine, amphetamines)
Pemoline --
Dextroamphetamine --
Pseudoephedrine --
Phenylephrine --
Phenylpropanolamine --
Selective serotonin reuptake inhibitors --
Modified from Eddy M, Walbroehl GS. Insomnia. Am Fam Physician 1999;59(7):1911 - 1916,1918.
TABLE 2.9.2 Differential Diagnosis of Insomnia
Primary insomnia
Psychophysiologic insomnia
Sleep related disordered breathing
Sleep apnea
Loud snoring
Hypnosia
Asthma
Circadian rhythm sleep disorders
Jet lag type
Delayed sleep phase type (more common in adolescents and young adults, usually very late bed times and late or midday wake times)
Advanced sleep phase type (more common in older adults, early bed time and early wake time)
Shift work type
Environmental disruptions
Loud noises
Bed partner with sleep disorder
Uncomfortable or unsafe sleeping conditions		 Extrinsic sleep disorders
Environmental sleep disorder (adverse sleep environment)
Alcohol-dependent insomnia
Hypnotic-dependent insomnia
Illicit drug use
Associated medical and psychiatric conditions
Alzheimer's and other dementia
Anxiety disorders
Asthma
Chronic obstructive pulmonary disease
Depressive disorders
Gastroesophageal reflux
Hyperthyroidism
Mania
Nocturia
Restless leg syndrome
Pain, acute, or chronic
Parkinson's disease
Periodic limb movement disorder
Modified from Eddy M, Walbroehl GS. Insomnia. Am Fam Physician 1999;59(7):1911 - 1916,1918 and Silber M, Krahn L, Morgenthaler T. Sleep medicine in clinical practice London: Taylor & Francis; 2004.
References
1. Espie CA, Morin CM. Insomnia a clinical guide to assessment and treatment. 2003.
2. Silber M, Krahn L, Morgenthaler T. Sleep medicine in clinical practice London: Taylor & Francis, 2004.
3. Schenck CH, Mahowald MW, Sack RL. Assessment and management of insomnia. JAMA 2003;289(19):2475 - 2479.
4. National Heart, Lung, and Blood Institute Working Group on Insomnia. Insomnia: assessment and management in primary care. Am Fam Physician 1999;59(11):3029 - 3038.
5. Eddy M, Walbroehl GS. Insomnia. Am Fam Physician 1999;59(7):1911 - 1916,1918.