Insomnia

Understanding Insomnia

Insomnia is the most common sleep disorder, characterized by difficulty falling asleep, staying asleep, or early morning awakening despite adequate opportunity for sleep, resulting in daytime impairment.

Diagnostic Criteria: Chronic Insomnia Disorder

According to ICSD-3 criteria, chronic insomnia requires:

• Difficulty initiating sleep, maintaining sleep, or early morning awakening with inability to return to sleep
• The sleep difficulty occurs despite adequate opportunity and circumstances for sleep
• At least one daytime consequence (fatigue, mood disturbance, impaired performance, cognitive dysfunction, concerns about sleep)
• Sleep difficulty occurs at least 3 nights per week
• Sleep difficulty present for at least 3 months
• Not better explained by another sleep disorder

Pathophysiology: The Hyperarousal Model

Chronic insomnia is increasingly understood as a disorder of hyperarousal—a state of heightened physiological, cognitive, and cortical activation that persists across 24 hours.

Neurobiological Hyperarousal

Insomnia patients demonstrate:

• Increased metabolic rate during sleep (measured by whole-body and brain glucose metabolism)
• Higher core body temperature in evening and during sleep
• Elevated cortisol and ACTH especially in evening/nighttime
• Increased sympathetic nervous system activity (elevated heart rate, reduced heart rate variability)
• Higher beta and gamma EEG power during NREM sleep (indicating increased cortical activation)

The 3P Model of Insomnia

Spielman's 3P model explains insomnia development:

• Predisposing factors: Genetic vulnerability, tendency toward anxiety/rumination, heightened stress reactivity
• Precipitating factors: Acute stressor triggering initial sleep disruption (medical illness, life event, work stress, trauma)
• Perpetuating factors: Maladaptive behaviors and cognitions that maintain insomnia after the precipitant resolves (irregular sleep schedules, excessive time in bed, sleep-related anxiety, caffeine/alcohol use)

Cognitive Behavioral Therapy for Insomnia (CBT-I)

CBT-I is the first-line treatment for chronic insomnia, recommended by all major sleep medicine societies. It is more effective than medications long-term, produces sustained benefits, and has no side effects.

Components of CBT-I

1. Sleep Restriction Therapy (SRT)

SRT consolidates sleep by initially restricting time in bed to match actual sleep time, creating mild sleep deprivation that increases homeostatic sleep drive and reduces sleep fragmentation.

• Calculate average total sleep time from sleep diary
• Set time in bed (TIB) = average total sleep time (minimum 5 hours for safety)
• Set consistent wake time
• Calculate bedtime = wake time - TIB
• When sleep efficiency ≥85% for 5 days, increase TIB by 15-30 minutes

2. Stimulus Control Therapy

Re-associate the bed/bedroom with sleep rather than wakefulness. Instructions:

• Go to bed only when sleepy
• Use bed only for sleep and intimacy—no reading, TV, phones, work
• If unable to fall asleep within 15-20 minutes, get out of bed and do quiet activity in dim light until sleepy
• Wake at same time every morning regardless of sleep amount
• No daytime napping

3. Cognitive Therapy

Address dysfunctional beliefs and anxieties about sleep. Common cognitive distortions in insomnia:

• "I need 8 hours of sleep or I can't function"
• "One bad night ruins my entire week"
• "I'll never be able to sleep normally again"
• "I have to fall asleep NOW or tomorrow will be terrible"

4. Sleep Hygiene Education

Optimize sleep environment and habits: cool, dark, quiet bedroom; limit caffeine after early afternoon; avoid alcohol; avoid large meals within 2-3 hours of bed; establish relaxing pre-bed routine; manage light exposure.

5. Relaxation Techniques

Reduce physiological and cognitive arousal: progressive muscle relaxation, diaphragmatic breathing, guided imagery, mindfulness meditation.

Pharmacological Treatment

Medications can be useful for insomnia but should ideally be time-limited and combined with CBT-I when treating chronic insomnia.

FDA-Approved Medications

• Z-drugs (Zolpidem, Eszopiclone, Zaleplon): Effective but risks include tolerance, dependence, residual sedation, falls, complex sleep behaviors
• Melatonin Receptor Agonists (Ramelteon): Safer profile, no abuse potential, less effective than BzRAs
• Orexin Receptor Antagonists (Suvorexant, Lemborexant, Daridorexant): Newer class, effective for sleep onset and maintenance, lower abuse potential
• Low-dose Doxepin: Antihistamine effect, FDA-approved for sleep maintenance

Off-Label Medications

• Trazodone: 25-100mg, very commonly prescribed despite limited evidence
• Mirtazapine: 7.5-15mg, useful when treating comorbid depression
• Gabapentin/Pregabalin: Can improve sleep, especially with comorbid RLS or pain