Educational resource only — this page helps students conceptualize diagnostic presentations and is not intended for clinical decision-making or self-diagnosis. Content may contain gaps or simplifications. Always verify against current clinical references and follow your institution’s protocols.
F51.01

Insomnia Disorder

Chronic Insomnia, Primary Insomnia
Diagnostic Category
Sleep-Wake Disorders
Key Features
  • Dissatisfaction with sleep quantity or quality with difficulty initiating, maintaining, or early morning awakening
  • Occurs at least 3 nights per week for at least 3 months despite adequate opportunity for sleep
  • Causes clinically significant distress or functional impairment
  • CBT-I is first-line treatment for chronic insomnia, superior to medications long-term
  • Must rule out obstructive sleep apnea, restless legs syndrome, circadian rhythm disorders, and substance/medication-induced sleep disturbance

Red Flags & Key Clinical Considerations

Obstructive Sleep Apnea Symptoms

Snoring, witnessed apneas, excessive daytime somnolence, morning headaches, obesity, hypertension. Screen with STOP-BANG in every insomnia patient. Prescribing sedative-hypnotics in undiagnosed OSA suppresses respiratory drive and is potentially life-threatening. A polysomnography referral is diagnostic.

REM Sleep Behavior Disorder

Dream enactment behaviors (talking, yelling, punching, kicking, falling out of bed during sleep), typically in men over 50. This is not insomnia. RBD is a prodromal marker for synucleinopathies, specifically Lewy body dementia and Parkinson's disease. The majority of RBD patients will develop a neurodegenerative disorder within 10-15 years. Requires polysomnography with EMG and neurological evaluation.

New-Onset Insomnia in Elderly Patients

Insomnia presenting for the first time in an elderly patient warrants a broader differential than chronic insomnia in younger adults. Consider delirium (especially in hospitalized or post-surgical patients), new or worsening depression, uncontrolled pain, medication effects (new medications, dosage changes, polypharmacy), medical conditions (heart failure with orthopnea, nocturia from BPH, GERD), and early neurodegenerative disease. New-onset sleep complaints in the elderly are a symptom until proven otherwise.

Related Medications

Medications commonly used in the treatment of insomnia disorder:

Practice With Related Cases

Practice identifying and managing insomnia disorder through these educational case studies:

References & Further Reading

This educational summary synthesizes information from standard clinical references for learning purposes. It is not a substitute for primary sources. Always verify against current clinical guidelines before applying any content in practice.

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