Difficulty initiating or maintaining sleep or nonrestorative sleep despite adequate opportunity and circumstances for sleep, resulting in at least one of the following forms of daytime impairment:

  • Fatigue or malaise
  • Attention, concentration, or memory impairment
  • Social or vocational dysfunction or poor school performance
  • Mood disturbance or irritability
  • Daytime sleepiness
  • Motivation, energy, or initiative reduction
  • Proneness for errors or accidents at work or while driving
  • Tension, headaches, or GI symptoms in response to sleep loss
  • Concerns or worries about sleep


  • Predominant age: increases with age
  • Predominant sex: female > male (5:1)


  • Insomnia (transient and chronic): 5–35% of the population; 10–15% associated with daytime impairment
  • Chronic insomnia: 10% middle-aged adults; 1/3 of people aged >65 years

Etiology and Pathophysiology

  • Transient/intermittent (<30 days) and short-term (<3 months)
    • Usually caused by an identifiable stressor
    • Stressor can be:
      • Physical (e.g., medical illness, high altitude)
      • Psychological (e.g., stress, excitement, bereavement)
      • Psychosocial (e.g., work deadlines, housing insecurity)
      • Interpersonal (e.g., arguments)
  • Usually resolves when stressor is removed
  • Chronic (>3 months)
    • Usually not due to one single cause
    • Possible contributing factors:
      • Medical (e.g., gastroesophageal reflux disease, sleep apnea, chronic pain)
      • Psychiatric (e.g., mood, anxiety, psychotic disorders)
      • Primary sleep disorder (e.g., idiopathic, psychophysiologic [heightened arousal and learned sleep-preventing associations], paradoxical [sleep state misperception])
      • Circadian rhythm disorder (e.g., irregular pattern, jet lag, delayed/advanced sleep phase, shift work)
      • Environmental (e.g., lights, noises, movements [partner/young children/pets])
      • Behavioral (e.g., poor sleep hygiene, adjustment sleep disorder)
      • Substance induced
      • Medications (e.g., antihypertensives, antidepressants, corticosteroids, levodopa-carbidopa, phenytoin, quinidine, theophylline, thyroid hormones)

No known factors

Risk Factors

  • Age
  • Female gender
  • Medical comorbidities
  • Unemployment
  • Psychiatric illness
  • Impaired social relationships
  • Shift work
  • Separation from spouse or partner
  • Drug and substance abuse
  • Family or personal history of insomnia

General Prevention

  • Practice consistent sleep hygiene:
    • Fixed wake-up times and bedtimes regardless of amount of sleep obtained (weekdays and weekends)
    • Avoid naps. Go to bed only when sleepy.
    • Sleep in a cool, dark, quiet environment.
    • No activities in bedroom associated with anything but sleep or sex
    • 30-minute wind-down time before sleep
    • If unable to sleep within 20 minutes, move to another environment and engage in quiet activity until sleepy.
  • Limit caffeine intake to mornings.
  • No alcohol after 4 PM
  • Fixed eating times
  • Avoid medications that interfere with sleep.
  • Regular moderate exercise

Commonly Associated Conditions

  • Psychiatric disorders
  • Painful musculoskeletal conditions
  • Obstructive sleep apnea
  • Restless leg syndrome
  • Drug or alcohol addiction/dependence

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