Obesity and upper airway soft tissue abnormalities are known risk factor and smoking multiplies the risk by 3 times. Even alcoholism,
nasal congestion, craniofacial abnormalities, hypothyroidism, acromegaly, and adenotonsillar hypertrophy can lead to such symptoms. Hence, the above mentioned conditions should be ruled out by physical examinations, thyroid profile and other blood tests.
Meantime you need to go for weight reduction exercises, and as well as dietary modification.