Types and Causes of Sleep Apnea

Sleep apnea is a period of reduced or no breathing. This period must be 10 seconds or more for the period to be defined as apnea. Hypopnea is defined by a reduction in the normal airflow. Oxygen is usually reduced by 4% or more for either apnea or hypopnea. Therefore, there are health implications, due to the significant decrease in oxygen with both apnea and hypopnea. The formal diagnosis of sleep apnea is when there are 15 or more periods in an hour. NOTE: In some patients who are already at high risk of health consequences, this number may be lowered.
There are two types of sleep apnea: central (less common) or obstructive (most common then central) The risk for sleep apnea is the same for men and women after the age of 50 years old. Usually, only adults have sleep apnea, however, in rare instances, infants, especially premature infants, also have sleep apnea.
Central apnea is due to the respiratory center in the brain not stimulating respirations. It may be caused by heart failure, congenital disorders, or cerebrovascular disease. In some cases, certain medications or a high altitude might increase the risk.
Obstructive apnea is due to collapse of one’s airway. The airway is composed of the nasal passages, soft palate, uvula, and pharynx. Anyone or more of these areas may be affected and contribute to obstructive sleep apnea. Causes range from deviated septums, loss of muscular control, or a narrow airway. It is significant to note that 70% of patients who are obese also have obstructive sleep apnea. The base of the tongue may also be involved.