What are the differences between sleep apnea and nocturnal hypoxemia?

2 different condtion. sleep apnea is when there is a cessation of airflow with sleep and breathing. The most common type of sleep apnea is obstructive sleep apnea when the upper airway gets blocked. Nocturnal hypoxia is a general term for low oxygen with sleep. Sleep apnea can cause nocturnal hypoxia, though many other conditions can cause nocturnal hypoxia without sleep apnea such as copd or heart disease.