L19 - Insomnia and Pain Lecture

Insomnia and Pain

Introduction

• Starting note on painsomnia: Insomnia exacerbated by pain conditions, causing significant distress for individuals, particularly those with conditions like Ehlers-Danlos Syndrome (EDS).

Insomnia Overview

Definition of Insomnia

• Insomnia is difficult to define. It can occur as a symptom, a disorder, or both.

  • Often starts as a symptom of another disorder and evolves into an independent disorder.

  • Heterogeneity: Insomnia varies in duration, types, and causes.

  • Severity fluctuates over time.

  • ICSD3 Definition: "A sleep complaint that occurs at least three times per week for at least three months, associated with daytime impairment."

Prevalence of Insomnia

• Affects approximately 1/3 of adults occasionally and 10-15% on a chronic basis.

• Acute insomnia: Often develops in response to stressful life events.

• Chronic insomnia: Can evolve when short-term sleep problems persist over time.

Insomnia Symptoms

Common Symptoms

• Difficulty falling asleep.

• Difficulty staying asleep.

• Early morning awakenings.

• Poor-quality sleep.

• Physical Symptoms:

  • Daytime impairment or fatigue.

  • Irritability, depression, or anxiety.

  • Difficulty concentrating, focusing on tasks, or remembering.

  • Increased errors or accidents.

Types of Insomnia

Insomnia Severity Index (ISI)

Overview

• The ISI contains seven questions whose numeric responses total a score. Respond according to your sleep pattern from the last month to derive:

  • Total Score: _

ISI Score Interpretation Guidelines

• 0 – 7 = No clinically significant insomnia

• 8 – 14 = Subthreshold insomnia

• 15 – 21 = Clinical insomnia (moderate)

• 22 – 28 = Clinical insomnia (severe)

Prevalence Statistics

Variability by Criteria

Study Designs on Insomnia

Cross-Sectional Survey

• Participants: 2,085 adults.

• Objective: Examine prevalence of insomnia and sleep disturbance by gender and age group.

• Measures: Self-reported symptoms.

Findings

• Prevalence in Women: Insomnia symptoms are greater in women, especially as they age.

Longitudinal Studies on Incidence and Persistence

Prospective Cohort Study

• Participants: >3,000 adults from the general population.

• Purpose: Determine insomnia incidence, persistence, and sex differences over time.

• Measures: Standardized criteria tracked yearly.

Findings

• About 14% developed insomnia in 5 years. Women had higher incidence and persistence across the follow-up.

• Overall population incidence increased from 4-5% at year 1 to over 12% by year 5, indicating chronic and progressive insomnia.

Models of Insomnia

Various Models

• Stimulus Control Model (1972)

• Three Factor Model (1987)

• Microanalytic Model (1993)

• Neurocognitive Model (1997)

• Two Factor Model (1997)

• Sleep Interfering-Interpreting Process Model (2000)

• Psychobiologic Inhibition Model (2002)

• Cognitive Model (2002)

• Neurobiologic Model (2011)

Stimulus Control Model

• Perlis et al.: This model explains learned associations between the bedroom and wakefulness.

• Key Concepts:

  • Under good stimulus control: High probability (odds ~1 in 2) of associating bed with sleep.

  • Under stimulus dyscontrol: Low probability (odds ~1 in 8) for sleep association due to many wakeful behaviors in bed (e.g., reading, worrying).

• Clinical Implications:

  • Techniques include:

  • Going to bed only when sleepy.

  • Using the bed solely for sleep and sex.

  • Leaving bed if unable to sleep in ~20 minutes.

  • Rising at the same time each morning.

  • Avoiding naps.

  • Purpose: Restore the bed-sleep association and reduce conditioned arousal.

Three Factor Model

• This model looks at interactions between predisposing, precipitating, and perpetuating factors.

• Key Concepts:

  • Predisposing Factors: Vulnerabilities (e.g., high arousal, anxiety) that increase susceptibility to insomnia.

  • Precipitating Factors: Triggers that initiate insomnia (e.g., stress, illness).

  • Perpetuating Factors: Maladaptive behaviors that maintain insomnia (e.g., worrying about sleep).

• Chronicity: Insomnia often begins after a stressful event but persists due to learned behaviors.

Cognitive Model

Explanation

• Maladaptive thoughts lead to anxiety and wakefulness, perpetuating insomnia.

• Key Concepts:

  • Individuals worry excessively about sleep, enhancing anxiety and physiological arousal, thus disrupting sleep.

• This results in a self-reinforcing cycle, maintaining chronic insomnia.

Neurobiologic Model

Explanation

• Patterns of brain activity contribute to insomnia persistence.

• Key Concepts:

  • Hyperactivity in arousal networks interferes with sleep promotion, leading to chronic wakefulness.

• Dysregulation of brain systems becomes a hallmark of chronic insomnia.

Insomnia and Medical Conditions

Common Co-morbid Conditions

• Medical:

  • Hyperthyroidism, chronic pain, cardiovascular disease, etc.

• Psychiatric:

  • Mood disorders, anxiety disorders, ADHD, etc.

Summary

• Insomnia is linked with both medical and psychiatric disorders, often intensifying the severity of conditions.

Bidirectional Relationship Between Pain and Sleep

Poor Sleep Leads to Pain

• Increased Pain Sensitivity: Poor sleep heightens pain response.

• Reducing Pain Threshold: Lower sleep duration equates to a diminished tolerance for pain.

• Increased Inflammation: Poor sleep raises inflammatory markers.

• Impaired Pain Regulation Systems: Reduced production of natural pain-modulating substances (e.g., endorphins).

Pain Disrupts Sleep

• Increased Arousal: Pain activates stress responses, interfering with sleep onset.

• Reduced Sleep Quality: Individuals report poor sleep due to pain interference leading to lighter sleep patterns.

Impact of Insomnia on Pain Studies

Observational and Experimental Studies

• Various studies confirm the reciprocal relationship between insomnia and pain severity, corroborating findings from numerous studies indicating chronic sleep disturbance exacerbates pain conditions.

Important Findings

• Fragmented and poor-quality sleep correlates with heightened pain experience, particularly in populations with established insomnia symptoms.

• Chronic sleep loss manifests in increased pain sensitivity, lower pain tolerance, and disrupted habituation mechanisms.

Medications and Sleep

• Morphine Efficiency: Poor sleep reduces the efficacy of pain medication, emphasizing the necessity of comprehensive treatment for insomnia in pain management.