Sleep Wake Disorders

Introduction

Sleep wake disorders are a crucial topic for the MCCQE1 exam, as they significantly impact patient quality of life and overall health. This comprehensive guide will help Canadian medical students prepare for questions related to sleep disorders on the MCCQE1, with a focus on Canadian guidelines and practices.

Classification of Sleep Wake Disorders

The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) classifies sleep wake disorders into several categories. Here's a breakdown of the main types:

Key Concepts for MCCQE1

1. Insomnia

Insomnia is one of the most common sleep disorders encountered in Canadian primary care settings.

2. Obstructive Sleep Apnea (OSA)

OSA is a breathing-related sleep disorder with significant health implications.

Diagnostic Criteria:

• Recurrent episodes of upper airway obstruction during sleep
• Associated with oxygen desaturation
• Often accompanied by loud snoring and daytime sleepiness

Management:

1. Continuous Positive Airway Pressure (CPAP) therapy
2. Lifestyle modifications (weight loss, alcohol reduction)
3. Oral appliances
4. Surgical interventions in select cases

3. Narcolepsy

Narcolepsy is a chronic neurological disorder characterized by excessive daytime sleepiness and sudden sleep attacks.

Key Features:

• Excessive daytime sleepiness
• Cataplexy (sudden loss of muscle tone triggered by strong emotions)
• Sleep paralysis
• Hypnagogic/hypnopompic hallucinations

4. Circadian Rhythm Sleep-Wake Disorders

These disorders involve a misalignment between the individual's sleep-wake cycle and the desired or required sleep-wake schedule.

Types:

• Delayed Sleep Phase Disorder
• Advanced Sleep Phase Disorder
• Irregular Sleep-Wake Rhythm
• Shift Work Disorder

Management:

• Light therapy
• Melatonin supplementation
• Sleep hygiene education
• Chronotherapy (gradual sleep schedule adjustments)

Canadian Guidelines for Sleep Disorders

The Canadian Sleep Society (CSS) and the Canadian Thoracic Society (CTS) provide guidelines for the diagnosis and management of sleep disorders in Canada.

Insomnia Management Guidelines

1. First-line treatment: Cognitive Behavioral Therapy for Insomnia (CBT-I)
2. Pharmacological interventions should be used short-term and in conjunction with CBT-I
3. Avoid long-term use of benzodiazepines due to risk of dependence

Obstructive Sleep Apnea Guidelines

1. Screening: Use validated tools like STOP-Bang questionnaire in primary care
2. Diagnosis: Polysomnography or home sleep apnea testing
3. Treatment: CPAP is the gold standard for moderate to severe OSA

Key Points to Remember for MCCQE1

1. Understand the diagnostic criteria for major sleep disorders
2. Know the epidemiology of sleep disorders in the Canadian population
3. Be familiar with first-line treatments and Canadian guidelines
4. Recognize the impact of sleep disorders on overall health and quality of life
5. Understand the role of sleep studies in diagnosis
6. Be aware of the special considerations for sleep disorders in pediatric and geriatric populations

Sample Question

A 45-year-old man presents with complaints of excessive daytime sleepiness for the past 6 months. His wife reports that he snores loudly and she has observed pauses in his breathing during sleep. He has a BMI of 32 kg/m² and a neck circumference of 43 cm. Which one of the following is the most appropriate next step in management?

• A. Prescribe modafinil for daytime sleepiness
• B. Refer for overnight polysomnography
• C. Start CPAP therapy immediately
• D. Recommend weight loss and reassess in 3 months
• E. Prescribe a sedative to improve sleep quality

Explanation

The correct answer is:

• B. Refer for overnight polysomnography

This patient presents with classic symptoms of obstructive sleep apnea (OSA): excessive daytime sleepiness, loud snoring, and observed apneas. He also has risk factors including obesity (BMI >30) and a large neck circumference (>40 cm in men).

According to Canadian guidelines, the next step in management for suspected OSA is to confirm the diagnosis with an overnight sleep study. Polysomnography is the gold standard for diagnosing OSA and determining its severity, which guides treatment decisions.

Option A (modafinil) is incorrect as it treats the symptom without addressing the underlying cause. Option C (starting CPAP) is premature without a confirmed diagnosis. Option D (weight loss) may be part of the management plan but is not the most appropriate next step. Option E (sedative) could potentially worsen OSA and is not recommended.

Remember, for the MCCQE1, it's crucial to follow evidence-based, stepwise approaches to diagnosis and management, aligning with Canadian guidelines.

References

1. Morin, C. M., et al. (2020). Insomnia disorder. Nature Reviews Disease Primers, 6(1), 1-20.

2. Canadian Thoracic Society. (2021). Canadian Thoracic Society 2021 guideline update: Diagnosis and treatment of sleep disordered breathing in adults. Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 5(6), 348-361.

3. Ohayon, M. M., et al. (2017). National Sleep Foundation's sleep quality recommendations: first report. Sleep Health, 3(1), 6-19.

4. Sateia, M. J. (2014). International classification of sleep disorders. Chest, 146(5), 1387-1394.

5. Canadian Sleep Society. (2018). Canadian Sleep Society Position Paper on the Use of Melatonin for Insomnia in Children and Adolescents. Retrieved from https://css-scs.ca/resources/brochures-handouts/ (opens in a new tab)