The main diagnostic standard is known as nocturnal polysomnography. This is normally carried out in a sleep laboratory, to which your doctor may refer you after examining the back of your mouth, nose and throat for abnormal swelling of tissues or extra tissue than normal. Your doctor might also check your blood pressure and measure the circumference of your waist and neck. If he or she believes you have OSA or even the beginnings of it, they might refer you to a sleep clinic.