Which of the following is a common symptom of sleep apnea?

Excessive daytime sleepiness is a hallmark symptom of sleep apnea. This condition causes repeated disruptions in breathing during sleep, leading to fragmented sleep and a lack of restorative rest. As a result, individuals with sleep apnea often struggle to stay awake and alert during the day, even after a full night's sleep. The repeated awakening, though often unconscious, means that the person does not progress through the full sleep cycles necessary for adequate recovery and alertness.

In contrast, difficulty falling asleep might be associated with various sleep disorders or stress, but it is not specific to sleep apnea. Increased energy levels at night can occur in some individuals but typically should not be expected in those suffering from sleep apnea, as the condition generally leads to overall fatigue rather than increased alertness. Consistent restful sleep is also contrary to the experience of those with sleep apnea, who frequently wake up feeling unrested despite being in bed for the appropriate amount of time.