Definition
Insomnia is a sleep disorder characterized by difficulty initiating sleep, maintaining sleep, or experiencing non-restorative sleep despite adequate opportunity and circumstances for rest. The condition leads to impaired daytime functioning such as fatigue, mood disturbance, cognitive impairment, and decreased quality of life.
Classification
By Duration
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Acute (short-term) insomnia: Lasts less than 3 months, often triggered by stress, illness, travel, or environmental changes
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Chronic insomnia: Persists for 3 months or more, occurring at least 3 nights per week
By Type
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Sleep-onset insomnia: Difficulty falling asleep
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Sleep-maintenance insomnia: Frequent awakenings or difficulty returning to sleep
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Late insomnia: Early morning awakenings with inability to return to sleep
Etiology
Primary insomnia – Occurs without another medical, psychiatric, or environmental cause
Secondary insomnia – Due to:
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Psychiatric disorders (e.g., depression, anxiety)
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Medical conditions (e.g., chronic pain, asthma, heart failure, gastroesophageal reflux disease)
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Medications (e.g., corticosteroids, stimulants, some antidepressants)
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Substance use (e.g., caffeine, nicotine, alcohol withdrawal)
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Environmental factors (e.g., noise, light, temperature)
Pathophysiology
Insomnia often involves dysregulation of the sleep–wake cycle, which is controlled by:
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The homeostatic sleep drive (builds with wakefulness)
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The circadian rhythm (regulated by the suprachiasmatic nucleus of the hypothalamus)
In chronic insomnia, hyperarousal of the central nervous system—manifested as increased metabolic rate, elevated cortisol levels, and enhanced brain activity—may prevent normal initiation and maintenance of sleep.
Clinical Features
Symptoms
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Difficulty falling asleep (>30 minutes)
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Frequent nocturnal awakenings
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Early morning awakening
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Non-restorative sleep
Daytime consequences
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Fatigue, sleepiness
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Irritability, mood swings
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Difficulty concentrating, memory problems
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Reduced performance at work or school
Diagnosis
Diagnosis is clinical, based on history and exclusion of other causes. Key steps:
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Detailed sleep history (bedtime, wake time, awakenings, naps, sleep environment)
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Use of sleep diaries or actigraphy for 1–2 weeks
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Screening for psychiatric or medical comorbidities
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Polysomnography if sleep apnea, periodic limb movement disorder, or other sleep disorders are suspected
Management
The treatment approach includes non-pharmacological and pharmacological interventions.
Non-Pharmacological Management (First-Line)
1. Cognitive Behavioral Therapy for Insomnia (CBT-I)
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Evidence-based first-line treatment for chronic insomnia
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Includes stimulus control, sleep restriction, relaxation techniques, and cognitive restructuring
2. Sleep Hygiene
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Maintain regular sleep and wake times
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Avoid caffeine, nicotine, and alcohol close to bedtime
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Create a dark, quiet, and comfortable sleeping environment
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Avoid heavy meals and vigorous exercise close to bedtime
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Limit screen exposure at night
3. Relaxation Training
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Progressive muscle relaxation
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Deep breathing exercises
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Meditation or mindfulness
Pharmacological Management
Used when non-pharmacological measures are insufficient or in acute insomnia. Use lowest effective dose for the shortest duration possible.
1. Benzodiazepine Hypnotics
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Examples: Temazepam 7.5–30 mg orally at bedtime; Triazolam 0.125–0.25 mg orally at bedtime
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Indications: Short-term use in severe insomnia
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Risks: Tolerance, dependence, cognitive impairment, falls in elderly
2. Non-Benzodiazepine Hypnotics (“Z-drugs”)
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Examples: Zolpidem 5–10 mg orally at bedtime; Zaleplon 5–10 mg orally at bedtime; Eszopiclone 1–3 mg orally at bedtime
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Benefits: Fewer residual effects than benzodiazepines, though dependence risk still exists
3. Melatonin Receptor Agonists
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Ramelteon 8 mg orally at bedtime
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Particularly useful for sleep-onset insomnia; low abuse potential
4. Sedating Antidepressants (useful when insomnia coexists with depression or anxiety)
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Trazodone 25–100 mg orally at bedtime
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Mirtazapine 7.5–15 mg orally at bedtime
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Caution: Daytime sedation, weight gain
5. Antihistamines (OTC, not recommended for long-term use)
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Diphenhydramine 25–50 mg orally at bedtime
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Side effects: Dry mouth, urinary retention, next-day drowsiness
6. Melatonin Supplements
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Dose: 1–5 mg orally 30–60 minutes before bedtime
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More effective for circadian rhythm disorders than chronic insomnia
Special Considerations
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Elderly patients: Avoid long-acting benzodiazepines and sedating antihistamines due to fall and cognitive risks
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Pregnancy: Prefer non-drug measures; certain medications are contraindicated
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Shift workers: May require tailored sleep scheduling and light therapy
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Comorbid psychiatric disorders: Treat underlying condition concurrently
Prognosis
Acute insomnia often resolves once the precipitating factor is addressed. Chronic insomnia may persist for years and requires ongoing management to prevent relapse. Untreated insomnia increases risk for depression, anxiety, cardiovascular disease, and reduced quality of life.
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