. Obstructive sleep apnoea was define as the cessation of airflow for at least 10s in the presence of respiratory effort. Hypopnea was defined as a greater than 50% reduction of airflow for at least 10s,a reduction in breathing of less than 50% , greater than 3% oxygen desaturation (ODI) or arousal for more than 10s. ODI was calculated according to the number of oxygen desaturation values greater than 3% per hour of sleep. the apnoea- hypopnoea index (AHI) was calculate as the average of the total number of pnoea and hypopnoea index greater than5.