According to the search results, a blood oxygen level at or below 88% is considered dangerously low for most people during sleep. Sleep-related hypoxemia is a disorder involving blood oxygen levels that fall to 88% or below for at least five minutes during sleep without hypoventilation or another sleep-related breathing disorder. In children, drops in oxygen saturation to 90% or below for five minutes or more may also meet the criteria for sleep-related hypoxemia. People with obstructive sleep apnea and COPD often have low oxygen levels in their blood. A normal blood oxygen level should be between 94% to 98% . Anything below 90% oxygen level is dangerous to the body and requires intervention.

It is important to note that different people experience different blood oxygen levels, so there is not one single number that can be identified as the best blood oxygen level to have, whether awake or asleep. Blood oxygen levels can vary slightly during sleep, and it is normal for a sleeper to have periods of slow or shallow breathing and short pauses in breaths. However, when pauses become frequent or last longer than ten seconds, the amount of oxygen circulating throughout the body begins to fall, and if the amount of oxygen in the blood gets abnormally low, the rest of the body cannot function appropriately.

If a person experiences low oxygen levels during sleep, it is important to investigate the underlying cause. Some people may not have symptoms despite having low oxygen levels during sleep, or they may experience only general feelings of fatigue or unrefreshing sleep. Convenient tests are available and should be used in conjunction with a doctor’s evaluation. If an individual has been diagnosed with sleep-related hypoxemia, their physician may recommend supplemental oxygen use while sleeping.