Insomnia - Clinical Overview

Definition

Insomnia is the complaint of difficulty initiating or maintaining sleep, or of unrefreshing sleep, resulting in daytime symptoms such as fatigue, irritability, impaired cognition, and reduced performance. The key distinction from simply needing less sleep is the presence of daytime sequelae.

Acute/Short-term insomnia: <3 months; affects >30% of adults
Chronic insomnia: >3 months; affects ~10% of adults

(Harrison's Principles of Internal Medicine 22E, Goldman-Cecil Medicine)

Epidemiology & Risk Factors

More common in women, older adults, lower socioeconomic status
Strong association with psychiatric and chronic medical illness
Personality traits: obsessive-compulsive tendency, frequent rumination, poor coping

Differential Diagnosis

The following chart from Goldman-Cecil shows the major categories:

Classification of Adult Insomnia

Category	Subtype	Description
Primary	Psychophysiologic	Conditioned arousal - associating bed with wakefulness; sleep better in new environment
	Idiopathic	Starts in childhood, lifelong; impaired intrinsic sleep mechanisms
	Paradoxical	Marked mismatch between subjective complaint and objective polysomnogram
Secondary	Adjustment insomnia	Acute psychosocial stressor
	Inadequate sleep hygiene	Lifestyle habits impairing sleep
	Comorbid psychiatric	Anxiety, depression, mania, PTSD, schizophrenia
	Comorbid medical	Renal/hepatic failure, pain, GERD, heart failure, hot flashes
	Drug/substance-induced	Medications, alcohol, caffeine, recreational drugs

History - The 3 "P" Framework

Predisposing factors - lighter-than-normal sleep baseline, anxious personality
Precipitating factors - illness, loss, job change, new medication
Perpetuating factors - maladaptive behaviors that maintain the insomnia

Key questions to ask:

Timing: difficulty falling asleep (delayed sleep phase, phobia) vs. early morning awakening (depression, advanced sleep phase)
Caffeine, alcohol, tobacco intake and timing
Medications review
Bed partner report (snoring, limb movements suggesting sleep apnea or RLS)
24-hour schedule and nap habits

(Harrison's 22E, Goldman-Cecil Medicine)

Common Contributing Factors

Psychiatric (~80% of psychiatric patients have sleep complaints)

Depression - classic early morning awakening, but also onset/maintenance problems
Anxiety - racing thoughts, rumination
Mania/hypomania - substantially reduced sleep
PTSD, schizophrenia

Medical

Pain (rheumatologic disorders, neuropathy)
Respiratory: asthma, COPD, heart failure, OSA
GERD, menopause (hot flashes)
Neurologic: dementia, Parkinson's disease
~60% of long-COVID patients report insomnia

Medications / Substances

Caffeine (half-life 6-9 h - can disrupt sleep up to 8-14 h after ingestion)
Alcohol (disrupts sleep architecture)
Many psychoactive, cardiovascular, and respiratory drugs

Poor Sleep Hygiene

Daytime napping
Irregular sleep-wake schedule
Screen use in bed (blue light suppresses melatonin)
Using the bedroom for work, TV, arguing

Treatment

Step 1 - Treat the Underlying Cause

Address any medical or psychiatric condition (pain, depression, GERD, etc.)

Step 2 - Sleep Hygiene (ALL patients)

Do	Avoid
Use bed only for sleep and sex	Napping, especially after 3 PM
Fixed bedtime and wake time every day	Caffeine after lunchtime
20-30 min wind-down routine (bath, meditation, reading)	Alcohol and smoking near bedtime
Dark, quiet, comfortable bedroom	Screens and smartphones in bed
If awake >20 min, get out of bed	Heavy meals or vigorous exercise within 2-3 h of bed

Step 3 - Cognitive Behavioral Therapy for Insomnia (CBT-I) - First-line

Cognitive restructuring - reframe faulty beliefs and worries about sleep
Stimulus control therapy - break conditioned bed-wakefulness association
Sleep restriction therapy - limit time in bed to consolidate sleep
Relaxation techniques - progressive muscle relaxation, meditation
Can be delivered online/digitally with similar efficacy

CBT-I is the standard first-line treatment and provides long-term success.

Step 4 - Pharmacotherapy (adjunct to CBT-I, short-term preferred)

Drug Class	Agents	Notes
BzRA (Z-drugs)	Zaleplon 5-20 mg (t½ 1-2h), Zolpidem 5-10 mg (t½ 2-4h), Eszopiclone 1-3 mg (t½ 5-8h), Temazepam 15-30 mg (t½ 8-20h)	Match half-life to problem (onset vs. maintenance). Use intermittently.
Benzodiazepines	Lorazepam, Triazolam, Clonazepam	First-line per Goldman-Cecil; risk of dependence with long-term use
Orexin antagonists	Suvorexant 10-20 mg, Daridorexant 25-50 mg, Lemborexant	Block hypocretin to promote sleep maintenance; newer agents
Melatonin receptor agonist	Ramelteon 8 mg	Good for sleep-onset issues; minimal dependence risk
Antidepressants	Trazodone, Doxepin	Useful when comorbid depression/anxiety present
Antihistamines	Diphenhydramine	OTC; tolerance develops quickly; avoid in elderly (anticholinergic effects)

Note: For comorbid depression/anxiety, combining a short-term hypnotic with a long-term antidepressant/anxiolytic is better than either alone.

Recent evidence (2025): A network meta-analysis found daridorexant, lemborexant, and suvorexant (orexin antagonists) are effective and safe for insomnia - daridorexant showing favorable tolerability. Melatonin timing and dosing optimization is also well-supported by recent meta-analysis.

Prognosis

Most patients improve; some relapse
CBT-I is key to long-term success
Chronic insomnia may herald an affective disorder and is associated with higher dementia risk in older adults
Sleep diary for 2 weeks is a useful tool in management
Polysomnography only if sleep apnea is suspected or multiple therapies have failed

(Goldman-Cecil Medicine, Harrison's 22E)

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