 [ Symptoms ] what type of underlying health problems can cause oxygen levels to drop at nighttime [ Disease ] the main condition that comes to mind is obstructive sleep apnea osa though congestive heart failure chf or even chronic obstructive pulmonary disorder copd also could cause nocturnal hypoxemia abnormally low blood oxygen levels at night if you believe you have abnormally low oxygen levels during sleep i would strongly suggest you have this symptom checked out by a medical professional untreated hypoxemia can have negative health consequences hope this helps