Symptoms of Obstructive Sleep Apnea

What are the symptoms of OSA?

Common symptoms include:

Fatigue
Non-restorative sleep
Nocturnal polyuria (Excessive urination at night)
Morning headaches
Irritability
Memory loss
Loud, disruptive snoring
Gasping during sleep
Choking during sleep
Apneas (cessation of breathing) during sleep
Excessive daytime sleepiness

Excessive daytime sleepiness is the most common symptom of OSA. Improvements to daytime sleepiness is the most significantly affected symptom following treatment. About 23% of women and 16% of men experience daytime sleepiness. However, it is difficult to link daytime sleepiness to apneic events since several factors can contribute to it.

Health problems that can arise from OSA

Long-term untreated OSA can increase the risk of several other medical conditions including:

Cardiovascular conditions

High blood pressure

There is evidence supporting a link between OSA and high blood pressure. Both conditions are common among the middle-aged and elderly. Animal models of OSA have shown a temporary increase in nighttime blood pressure is OSA animals that developed into chronic daytime high blood pressure. Temporary stabilization of blood pressure has also been shown to reduce episodes of sleep apnea in animals with high blood pressure.

Studies in humans have also found that nearly half of individuals with OSA have high blood pressure, while 30% of individuals with high blood pressure have OSA.

High blood pressure and OSA also have similar risk factors such as abnormal upper airway dilator muscle behavior, reduced lung volume, age, sex, obesity, ethnicity and impaired ventilator control stability.

There are different forms of high blood pressure that occur during OSA such as:

High blood pressure at night (nocturnal hypertension)
High blood pressure that cannot be reduced by treatment with drugs (Resistant hypertension)
Blood pressure that is normal in the clinic, but high outside of the clinic (Masked hypertension)
High blood pressure affecting the arteries of the lungs and heart (Pulmonary hypertension)

Several mechanisms may contribute to the link between OSA and high blood pressure including intermittent hypoxia, endothelial dysfunction, inflammation and oxidative stress.

Coronary artery disease

OSA can cause several problems in coronary artery disease. OSA has been shown to promote coronary atherosclerosis- the buildup of cholesterol, fats and other substances in the coronary arteries. The severity of OSA correlates with severity of the coronary artery disease.

OSA results in repeated hypoxia and reoxygenation. This can lead to increased oxidative stress which can cause vascular damage and lipid peroxidation. Endothelial cell dysfunction is also linked to OSA. Impairment prevents the vasculature from relaxing causing the onset of atherosclerosis.

OSA is also associated with a high level of inflammation related factors in the blood. Chronic hypoxemia has been linked to increased activity in inflammation pathways. Together, these inflammatory pathways can promote atherosclerosis. Through promotion of atherosclerosis, OSA accelerates damage to the arteries related to coronary artery disease. However, early signs of atherosclerosis do respond to OSA treatments such as CPAP.

OSA also promotes thrombosis (clotting in the circulatory system) and coagulation through oxygen desaturation and reduction of fibrinogen levels and activity. Clotting has also been shown to improve with CPAP treatment.

Myocardial ischemia, a reduction of blood flow to the heart resulting in reduced oxygen delivery to heart tissues, may be influenced by OSA. OSA can increase the oxygen needed by the heart during apnea. Because oxygen levels are already reduced by the apneic episode, this can lead to myocardial ischemia.

Congestive heart failure

Sleep disordered breathing increase the risk of heart related diseases by increasing the pressure on the heart ventricles which can cause arrhythmias and pulmonary congestion. Sleep disordered breathing also increases waking during sleep, which increases sympathetic activity, blood pressure and heart rate, and decreases in parasympathetic activity. Apneas and hypopneas (shallow breathing) reduce oxygen and increase carbon dioxide in the blood temporarily. These episodes are followed by a compensatory increase in oxygen and decrease in carbon dioxide, causing major swings in oxygen and carbon dioxide levels in the blood. These major changes increase sympathetic activity. OSA increases the mortality, hospitalization, organ transplants needed and death in individuals with heart failure. Similarly, treatment of OSA improves survival.

Stroke

Similar to other cardiovascular conditions, OSA increases the risk of stroke by causing an increase in sympathetic activity, endothelial dysfunction, elevated fibrinogen levels, increased platelet activation during sleep, altering platelet agreegability, hypercoagulability and decreased cerebral blood flow in sleep apnea. One study found that approximately 74% of patients with ischemic stroke also suffered from OSA. Other studies have reported that OSA is as common as 37% to 79% in individuals with stroke. Treatment of OSA in patients with stroke can prevent the onset of following stokes. Treatment with CPAP, as with other cardiovascular diseases, has been shown to have beneficial effects in reversing or preventing additional cardiovascular disorders.

Metabolic disorders

o Diabetes

OSA occurs in approximately 71% of diabetes cases. Some studies have found that the alteration in sleep cycles may decrease growth hormone, a hormone that plays a vital role in body composition of body fat, muscle and abdominal fat. OSA may also promote the development of diabetes through promoting insulin resistance.

Cognitive impairment

OSA has been associated with cognitive impairment. This impairment is through to result from a variety of related effects of OSA including intermittent hypoxia, hormone imbalance, inflammation and endothelial dysfunction. Many studies have found that hippocampal volume is decreased in individuals with OSA and neurocognitive dysfunction. Other altered areas include the frontal and parietal lobes. These alterations can be partially reversed through treatment with CPAP.

Depression

Depression has also been linked to OSA. Specifically there is an association with the frequency of snorting and apnea during sleep with the likelihood of depression. Individuals with depression are 5 times more likely to suffer from sleep-disordered breathing. As with other conditions linked to OSA, treatment of OSA has been shown to improve depression symptoms.

Cardiac Arrhythmia

Individuals with severe OSA were 2 to 4 times more likely to have complex arrhythmias than individuals without OSA. This association was especially high for individuals with atrial fibrillation.

OSA can also have effects on daily living such as: