Insomnia
Definitions and diagnosis
Chronic insomnia disorder is difficulty initiating or maintaining sleep, or early-morning awakening, with daytime consequences, occurring at least three nights per week for at least three months despite adequate opportunity for sleep. It is a clinical diagnosis; polysomnography is not required and is reserved for suspected comorbid disorders (apnea, periodic limb movements, or when the history is atypical).
Mechanisms and comorbidity
The 3P model (predisposing, precipitating, perpetuating) explains chronification; hyperarousal (cognitive, physiologic, and cortical) is the central maintaining factor. Insomnia frequently co-occurs with depression, anxiety, and chronic pain, and it is itself a risk factor for incident depression. Recognize conditioned arousal, sleep-state misperception, and maladaptive behaviors (long time in bed, daytime napping, irregular schedule).
Treatment
Cognitive behavioral therapy for insomnia (CBT-I) is first-line for chronic insomnia in adults and includes stimulus control, sleep restriction, cognitive restructuring, relaxation, and sleep hygiene. Sleep restriction uses time-in-bed titration to build sleep pressure; stimulus control re-associates the bed with sleep. Pharmacotherapy is adjunctive: avoid long-term benzodiazepines and Z-drugs, especially in older adults (falls, cognitive effects); note that sedating antidepressants are used off-label and carry their own risks. Treat comorbid conditions but do not assume insomnia resolves when they do.
Traps
Questions conflate primary and comorbid insomnia, or offer sleep hygiene alone as adequate therapy (it is necessary but insufficient). Distinguish hypnotic-rebound insomnia from worsening disease. Watch stems asking about older adults, where nonpharmacologic therapy is strongly preferred.
Worked example
A patient sleeping 5 hours nightly but spending 9 hours in bed: the therapeutic lever is reducing time in bed (sleep restriction), not adding a hypnotic.