What is a primary characteristic of obstructive sleep apnea?

Obstructive sleep apnea is primarily characterized by apneas that occur due to airway blockage. In this condition, the throat muscles relax excessively during sleep, which can lead to partial or complete obstruction of the airway. This obstruction prevents air from flowing into the lungs, resulting in periods of apneas or interrupted breathing.

As the body and brain sense the lack of oxygen, the individual may partially awaken to reopen the airway, leading to disrupted sleep patterns and reduced overall sleep quality. This distinctly differentiates obstructive sleep apnea from central sleep apnea, where the problem originates with the brain's signaling mechanisms.

The other options do not accurately represent the defining features of obstructive sleep apnea. Apneas due to brain failure to send signals relate more to central sleep apnea. While prolonged periods of wakefulness can occur due to the disturbances caused by obstructive sleep apnea, they are not the primary characteristic of the condition itself. Continuous positive airway pressure (CPAP) is a common treatment for obstructive sleep apnea, but it is not a characteristic of the apnea itself.