Emphysema and Sleep

What is emphysema?

Emphysema is a progressive chronic obstructive pulmonary disease (COPD) characterized by persistent respiratory symptoms and airflow limitation. The most common cause of emphysema is cigarette smoking; however, significant exposure to noxious gases, such as biomass fuels, and other environmental pollutants, such as sulphur dioxide and particulate matter, are recognized as important causes in developing countries. Also, 1% to 2% of patients have a hereditary autosomal recessive disease, alpha-1 antitrypsin deficiency, which leads to emphysema and liver abnormalities.¹

Symptoms

COPD non-specific symptoms include chronic shortness of breath and cough with or without sputum production, as well some patients present wheezing because of airflow obstruction. As the disease progresses, the shortness of breath and cough progressively worsen. Initially, dyspnoea (difficulty to breath) occurs with significant physical activity and evolves to dyspnoea with simple daily activities and even at rest. During disease advancement, patients can lose body weight due to systemic inflammation and energy spent breathing, and exacerbations could become more frequent as the obstruction of the airways increases. These exacerbations result in increased shortness of breath, increased severity of cough and increased sputum, typically brought on by an infection or an environmental factor.¹

Why is emphysema more disruptive at night?

Lying down

When lying down, some physiological changes in pulmonary function occur in subjects with COPD. The supine position (lying horizontally with the face and torso facing up) reduces the air volume in the lungs after a passive expiration. This volume, called functional residual capacity (FRC), maintains the equilibrium between the chest thoracic and lung. Normally, augmented in patients with COPD, FRC could be reduced significantly in a supine position, leading to the closing of small airways in dependent zones of the lung (those that are directly exposed to gravity force – in this case, the back). This phenomenon causes a reduction of gas exchange in capillaries, dropping oxygen levels (desaturation) and augmenting carbon dioxide in the blood (hypercapnia).² 

Hormonal circadian rhythm changes

Circadian rhythms (circa = about, dies = day) are patterns of our body physiology that follow a 24-h cycle. Patients with COPD have abnormalities in circadian rhythms, which are reflected in changes in respiratory symptoms and lung function, sometimes worsening in the early morning upon awakening, others complain of nocturnal symptoms. Circadian rhythm affects airway calibre, for example, which may be partly responsible for nocturnal exacerbations and worsening of oxygen levels in the blood in patients with COPD. However, very little is known about circadian changes in COPD.³

Sleep disturbances caused by emphysema

Night-time symptoms are a forgotten dimension of COPD. Especially patients with severe illnesses commonly have distinct abnormalities related to sleep that include poor sleep quality. Some of these are described here. 

Obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is characterized by episodes of a complete collapse of the airway or partial collapse with an associated decrease in oxygen saturation or arousal from sleep. This disturbance results in fragmented, nonrestorative sleep, which leads to excessive daytime sleepiness as one of the most common symptoms. The severity of upper airway narrowing during sleep is often related to body mass index, indicating that anatomical and neuromuscular factors contribute to airway obstruction. OSA is usually associated with COPD, and the coexistence of OSA and COPD has been described as “overlap syndrome”.⁴

Transient nocturnal desaturation

Transient nocturnal desaturation or the temporary drop in oxygen levels during sleep is a common symptom in patients with COPD. During all sleep stages, the respiratory centre in the central nervous system has diminished activity and respiratory muscle responses, especially those involving accessory muscles of respiration, to respiratory centre outputs are also diminished, particularly during REM sleep (a stage of sleep associated with dreaming and memory consolidation). All these respiratory inputs reduced results in a drop of oxygen concentration in blood (blood saturation) that in normal subjects is not significant. However, because many patients with COPD already have below-normal levels of oxygen in their blood even while awake, they are especially prone to nocturnal oxygen desaturation.⁵

Tips for better sleep with emphysema 

Several interventions improve sleep quality in patients with COPD. First of all, the adoption of optimal treatment of COPD to minimize symptoms such as cough, secretions and dyspnoea will likely lead to better sleep quality. Smoking cessation should be strongly encouraged, and other daytime habits that might contribute to insomnia (e.g., nicotine use, alcohol and caffeine intake). Other interventions such as oxygen supplementation may theoretically have several salutary effects on sleep in patients with COPD, but still, need larger studies to be proven. Also, therapy for attendant anxiety and depression helps to improve sleep in some cases. However, both should be recommended by a doctor in accordance with the severity of sleep disturbance.⁶ 

Conclusion

Patients with COPD suffer from several disturbances in sleep. Most of them are related to pathological changes in the respiratory system, which worsen due to circadian rhythms. However, some tips could help to improve sleep quality, especially an optimal treatment to minimize symptoms.