Pauses in breathing are nearly always accompanied by snoring between apnea episodes, although not everyone who snores has sleep apnea. Another sign of possible sleep apnea may be a choking sensation. The frequent interruptions of deep, restorative sleep often lead to early morning headaches and excessive daytime sleepiness.

Apnea occurs when the throat muscles and tongue relax during sleep and partially block the opening of the airway. During the apneic event, the person is unable to breathe in or exhale. That causes low levels of oxygen and increased levels of carbon dioxide in the blood, which alerts the brain to resume breathing and wakes the person. When the sleeper wakes, the brain signals the upper airway muscles to open and breathing is resumed, often with a loud snort or gasp. Frequent waking can prevent a person from getting enough restorative, deep sleep.

Among the tests available to help physicians diagnose sleep apnea are:

• Polysomnography: A test that records a variety of body functions during sleep, such as the electrical activity of the brain, eye movement, muscle activity, heart rate, respiratory effort, airflow and blood oxygen levels.
  
  
• Multiple Sleep Latency Test (MSLT): A test that measures the speed of falling asleep. People without sleep problems usually take an average of 10 to 20 minutes to fall asleep. People who fall asleep in less than five minutes are likely to require treatment for sleep disorders.