Chapter 34.3, Problem 1CSC

If you have sleep apnea, you never get a good night’s sleep. Although you may not realize it, your sleep is briefly interrupted from 30 to more than 100 times each night when you tempo­rarily stop breathing for 10 to 60 seconds (“apnea” means “without breath”). Your blood O₂ falls and CO₂ rises, causing you to partially awaken, often with a snort. What causes this? Obstructive sleep apnea, the most common form, occurs when muscles that support the tongue and soft tissues of the pharynx relax, causing these tissues to collapse and obstruct the airway. People who snore, are overweight, drink alcohol before bed, or smoke are all more susceptible to sleep apnea. The resulting daytime drowsiness, making it hard to concentrate and danger­ous to drive, is bad enough. But the repeated O₂ deprivation and CO₂ buildup caused by sleep apnea puts your heart at risk as well, so this is a condition to take seriously. How does your body know that you have stopped breathing?