The Relationship Between Sleep Apnea and Low Blood Oxygen Levels

Patients who develop sleep disturbances often seek the aid of a physician who commonly refers them for sleep studies. Sleep studies can yield important diagnostic information about a person's sleep cycles, oxygen levels, and the quantity and length of breathing interruptions.

What is the relationship between obstructive sleep apnea and lower oxygen levels during sleep? How does sleep apnea lead to oxygen desaturations that may affect overall health?

One of the most common sleep disorders diagnosed in people with difficulty sleeping is obstructive sleep apnea (OSA). The condition affects more than millions of Americans and can be serious. Information gathered during a sleep study can guide a physician in making the diagnosis.

Obstructive sleep apnea occurs when there is a blockage of air flow through the throat during sleep when a person's upper airway collapses during sleep. When this happens, breathing stops for as little as 10 seconds and even up to a minute or longer.

People with sleep apnea experience frequent, repeated episodes during a single night, sometimes hundreds. And while the person may sleep right through the episodes completely unaware of them, often a partner will notice and become alarmed.

During periods of apnea, people received less air, which results in decreased oxygen delivery to the body. The oxygen levels in the blood may fall repeatedly. This oxygen decrease is called an oxygen desaturation. It often drops by 3 or 4 percent (and sometimes much more) in association with sleep apnea events.

Oxygen levels are considered abnormal when they drop below 88 percent. These might be deemed to be severely abnormal when the levels drop below 80 percent. When the oxygen levels are low for more than 5 minutes during the night, this is a condition called hypoxemia.

Due to disrupted breathing in sleep, sleep apnea can cause people to feel drowsier the next day. In addition, without treatment, sleep apnea can result in any of the following signs and symptoms:

• High blood pressure
• Loud snoring
• Cardiovascular disease
• Weight gain
• Memory problems
• Impotency
• Headaches
• Depression
• Irritability
• Dry mouth upon awakening
• Snorting, gasping, choking during sleep
• Insomnia

People of any age, gender or weight can develop obstructive sleep apnea, but the disorder is more common among those who are:

• Obese
• Middle-aged (between 40 and 60 years old) or older
• Male
• Men with a neck circumference of 17 inches or greater; women with a neck circumference of 16 inches or greater
• Enlarged tonsils and/or adenoids
• Smokers
• Users of alcohol, sedatives, or tranquilizers

There are various lifestyle modifications that are often very successful in curing sleep apnea for some people. These include:

• Losing weight: Modest weight loss can help provide relief of apnea, and greater weight loss can even cure the disorder if this is the primary cause of the condition.
• Changing sleep position: Sleeping on the side or stomach may improve sleep apnea because back sleeping allows the tongue and soft palate to shift back into the throat, blocking the airway.
• Avoiding alcohol, tranquilizers, and sleeping pills: These can relax the muscles in the back of the throat causing it to collapse during sleep.
• Keep nasal passages clear: Using a saline nasal spray or a neti pot (a small pot used to pour water into the nostrils) can clear nasal passages, allowing increased airflow.

When lifestyle treatments fail, or for patients with more dramatic oxygen desaturation changes, a treatment known as continuous positive air pressure (CPAP) therapy can be very effective. CPAP machines blow air into the nose and/or mouth, creating a gentle pressure of air that pushes the throat open. This prevents it from collapsing during sleep and averts apnea.