Overview of Transient Nocturnal Desaturation in COPD

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Transient nocturnal desaturation is a serious problem that is commonly associated with chronic obstructive pulmonary disease (COPD). It does not typically cause immediate symptoms, but it can have harmful effects on your health over time.

When the oxygen concentration (the level of oxygen that your blood is carrying) in your blood temporarily becomes lower than usual while you are asleep at night—this is described as transient nocturnal desaturation.

You may need a sleep study to identify the condition, and nighttime therapeutic oxygen is usually prescribed to help alleviate the effects.


Sometimes, a night of transient nocturnal desaturation in COPD can make you feel that you did not get enough rest or that you are low in energy the next day. You may not notice distinct symptoms of transient nocturnal desaturation in COPD, but it can have slowly progressive long term effects on your lung function, blood pressure, heart, and brain health.

Pulmonary Function

A gradual decline in lung function can result from transient nocturnal desaturation. The lungs can undergo changes, such as worsening COPD and/or a condition called pulmonary hypertension. These pulmonary issues cause fatigue and shortness of breath all day, not just during sleep.

Cardiac Function

Transient nocturnal desaturation is associated with heart conditions such as arrhythmias (heart rate abnormalities) and heart failure. You may experience edema (swelling of your legs), low energy, dizziness, and/or palpitations (a feeling that your heart is racing) with these conditions.

Blood Vessels

Hypertension and arteriopathy are blood vessel conditions that are associated with transient nocturnal desaturation. Neither of these conditions causes noticeable symptoms, but they increase the risk of serious issues such as heart attack and stroke.

Brain Health

Brain health can be compromised during periods of transient nocturnal desaturation. Ischemic damage, which occurs due to severely low oxygen during a stroke, can be exacerbated when your brain is low in oxygen—worsening the effects of a previous stroke.

Sleep disorders such as sleep apnea commonly co-exist with COPD, and may further increase problems and symptoms associated with transient nocturnal desaturation.


COPD is a lung disease, and it causes a decrease in blood oxygen saturation levels during the day and at night. Oxygen is needed to sustain the organs throughout your body (like your heart, brain, and muscles). Red blood cells carry oxygen from the lungs to the cells of the body.

When the red blood cells are full, or near full, they are described as saturated (with oxygen). Normal oxygen saturation levels range between 95% and 100%, with red blood cells operating close to or at full oxygen-carrying capacity.

In COPD, the lungs cannot expand as they normally would. Oxygen flow and blood flow become obstructed, so the oxygen cannot flow easily into the red blood cells. You may have daytime oxygen saturation levels below 93% with COPD.

If you have the COPD, your breathing can be even further impaired while you sleep. Lower daytime oxygen saturation in COPD is commonly associated with transient nocturnal desaturation.

Effects of COPD on Nocturnal Oxygen Saturation

With COPD, you may experience hypoventilation (a slowed breathing rate) during sleep, which reduces the overall amount of oxygen that you take in, causing transient nocturnal desaturation.

COPD also commonly causes a ventilation/perfusion mismatch during sleep, which means the timing of your breathing is mismatched with the timing of blood circulating through your lungs. Your blood will not be able to pick up oxygen efficiently—and this results in low oxygen saturation.


If you have COPD, your doctor may give you screening tests to identify whether you also have transient nocturnal desaturation. At-home, non-invasive tests, as well as long term overnight tests in a supervised medical setting can help detect transient nocturnal desaturation.

Home oximetry is an at-home test that your doctor may prescribe for you to use on your own. This involves placing a small clip-on device on your finger to measure your oxygen saturation level while you sleep. Your doctor will receive a report of your oxygen levels. Some home oximeters also have an alarm that sounds when oxygen saturation falls below a certain level.

With transient nocturnal desaturation, your oxygen saturation level would be expected to drop more than 4% below your normal daytime level for at least five minutes while you are asleep.

Sleep Study

Another tool that is useful in identifying transient nocturnal desaturation and other sleep disorders is an overnight polysomnograph (PSG) (sleep study).

Sleep studies are performed in a dedicated sleep center. When you're undergoing a sleep study, you'll be monitored by a trained technician. The study equipment simultaneously records various physiological parameters that are related to sleep and wakefulness, including breathing, heart rate, oxygen levels, muscle activity, and eye movements.

Blood Tests

While a pulse oximeter can approximate your blood oxygen saturation, an arterial blood test is more precise. An alteration in oxygen saturation can be measured with an arterial blood gas sample. This test can be used to detect hypercapnia (too much carbon dioxide) and hypoxemia (too little oxygen). Changes in these levels will occur during sleep if you have transient nocturnal desaturation.


Transient nocturnal desaturation in COPD cannot be cured, but it can be managed. There are two main approaches used in managing transient nocturnal desaturation—oxygen therapy and mechanical ventilation. You may need one or both of these therapies to help improve your oxygen saturation during sleep.

If your treatment is effective, you may start to notice an improvement in your daytime energy level.

Oxygen Therapy

Oxygen therapy can increase the amount of oxygen that you take in with each inspiration, which improves your blood oxygen saturation. You can place a small plastic tube with two small plastic prongs in your nostrils. The prongs have openings through which oxygen is delivered in your nose.

Alternatively, a face mask can be placed over your nose and mouth to deliver oxygen.

When you use an oxygen machine at home, you will be given safety instructions. For example, your oxygen source should not be near an open flame.

If you are already using oxygen during the day for your COPD, your doctor may prescribe a higher oxygen concentration for you during your sleeping hours to prevent episodes of transient nocturnal desaturation.

Machine Ventilation

Mechanical ventilation is another approach used for the treatment of transient nocturnal desaturation. This involves machine-based assistance with breathing to help alleviate problems such as hypoventilation. The machine delivers a small amount of pressure to help your chest and lungs expand as you breathe.

A Word From Verywell

Transient nocturnal desaturation is not a noticeable effect of COPD. But it can have serious health consequences. If you have advanced COPD, your doctor will likely screen you for transient nocturnal desaturation. Keep in mind that the condition is not curable, and the best way to prevent it from worsening is to avoid factors that exacerbate COPD—such as smoking,

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