| [ Summary ] |
Obstructive sleep apnea syndrome (OSAS) is characterized by repeated obstruction of the upper airway during sleep. Upper airway obstruction during sleep occurs due to anatomical or functional abnormalities. Obesity is associated with the upper airway anatomy. Most patients with OSAS are obese and habitual snorers. As they have abundant lipid deposition and soft tissue in the upper airway, their upper airway is narrow while awake and is obstructed easily during sleep. Therefore, it seems that obesity is the most important risk factor in the development of OSAS. However, the prevalence of SAS is similar in Japan, the US and European countries, despite the fact that US and European people tend to be more obese than Japanese. This fact suggests that other factors play important roles in development of OSAS in Japan. |