In the majority of cases, persistent insomnia is associated with stress, psychiatric comorbidities, medical comorbidities, drug and substance misuse (drugs, nicotine, alcohol or caffeine), or current medication. However, in up to 20% of people with persistent insomnia, there is no associated cause or comorbidity61.

A 1996 World Health Organization survey indicated that 52% of people reporting a sleep problem had a well-defined mental health disorder and 54% reported a physical disorder63.

Possible causes of insomnia61

  • Other sleep disorders

    • Sleep apnoea
    • Circadian rhythm disorders such as shift work, jet lag, advanced sleep phase syndrome and delayed sleep phase syndrome
    • Parasomnias such as restless legs syndrome, periodic limb movement disorder, sleep talking, sleep walking, sleep terrors, teeth grinding, nightmare disorder
    • Narcolepsy
  • Stress

    • Situational stress (for example occupational, interpersonal, financial, academic, medical)
    • Environmental stress (for example noise)
  • Psychiatric comorbidities

    • Mood disorders: depression, bipolar disorder
    • Anxiety disorders: generalized anxiety disorder, panic disorder, post-traumatic stress disorder
    • Psychotic disorders: paranoia, schizophrenia
  • Medical comorbidities

    • Cardiovascular: angina, congestive heart failure
    • Respiratory: chronic obstructive pulmonary disease, asthma
    • Neurological: Alzheimer's disease, Parkinson's disease
    • Endocrine: thyroid dysfunction
    • Rheumatological: fibromyalgia, chronic fatigue syndrome, osteoarthritis, rheumatoid arthritis
    • Gastrointestinal: gastroesophageal reflux disease, irritable bowel syndrome
    • Genito-urinary: incontinence, benign prostatic hypertrophy, nocturia
    • Chronic pain
  • Drug and substance misuse

    • Alcohol
    • Recreational drugs
    • Caffeine
    • Nicotine
  • Medications including:

    • Antidepressants: selective serotonin reuptake inhibitors, venlafaxine, bupropion, duloxetine, monoamine oxidase inhibitors
    • Antiepileptics: lamotrigine, phenytoin
    • Antihypertensives: beta-blockers, calcium-channel blockers
    • Hormones: corticosteroids, thyroid hormones
    • Nonsteroidal anti-inflammatory drugs
    • Stimulants: methylphenidate, modafinil
    • Sympathomimetics: salbutamol, salmeterol, theophylline, pseudoephedrine

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