This is a medical question of type : exams and tests 
 How to diagnose Sleep Apnea ? 
 Doctors diagnose sleep apnea based on medical and family histories, a physical exam, and sleep study results. Your primary care doctor may evaluate your symptoms first. He or she will then decide whether you need to see a sleep specialist.
                
Sleep specialists are doctors who diagnose and treat people who have sleep problems. Examples of such doctors include lung and nerve specialists and ear, nose, and throat specialists. Other types of doctors also can be sleep specialists.
                
Medical and Family Histories
                
If you think you have a sleep problem, consider keeping a sleep diary for 1 to 2 weeks. Bring the diary with you to your next medical appointment.
                
Write down when you go to sleep, wake up, and take naps. Also write down how much you sleep each night, how alert and rested you feel in the morning, and how sleepy you feel at various times during the day. This information can help your doctor figure out whether you have a sleep disorder.
                
You can find a sample sleep diary in the National Heart, Lung, and Blood Institute's "Your Guide to Healthy Sleep."
                
At your appointment, your doctor will ask you questions about how you sleep and how you function during the day.
                
Your doctor also will want to know how loudly and often you snore or make gasping or choking sounds during sleep. Often you're not aware of such symptoms and must ask a family member or bed partner to report them.
                
Let your doctor know if anyone in your family has been diagnosed with sleep apnea or has had symptoms of the disorder.
                
Many people aren't aware of their symptoms and aren't diagnosed.
                
If you're a parent of a child who may have sleep apnea, tell your child's doctor about your child's signs and symptoms.
                
Physical Exam
                
Your doctor will check your mouth, nose, and throat for extra or large tissues. Children who have sleep apnea might have enlarged tonsils. Doctors may need only a physical exam and medical history to diagnose sleep apnea in children.
                
Adults who have sleep apnea may have an enlarged uvula (U-vu-luh) or soft palate. The uvula is the tissue that hangs from the middle of the back of your mouth. The soft palate is the roof of your mouth in the back of your throat.
                
Sleep Studies
                
Sleep studies are tests that measure how well you sleep and how your body responds to sleep problems. These tests can help your doctor find out whether you have a sleep disorder and how severe it is. Sleep studies are the most accurate tests for diagnosing sleep apnea.
                
There are different kinds of sleep studies. If your doctor thinks you have sleep apnea, he or she may recommend a polysomnogram (poly-SOM-no-gram; also called a PSG) or a home-based portable monitor.
                
Polysomnogram
                
A PSG is the most common sleep study for diagnosing sleep apnea. This study records brain activity, eye movements, heart rate, and blood pressure.
                
A PSG also records the amount of oxygen in your blood, air movement through your nose while you breathe, snoring, and chest movements. The chest movements show whether you're making an effort to breathe.
                
PSGs often are done at sleep centers or sleep labs. The test is painless. You'll go to sleep as usual, except you'll have sensors attached to your scalp, face, chest, limbs, and a finger. The staff at the sleep center will use the sensors to check on you throughout the night.
                
A sleep specialist will review the results of your PSG to see whether you have sleep apnea and how severe it is. He or she will use the results to plan your treatment.
                
Your doctor also may use a PSG to find the best setting for you on a CPAP (continuous positive airway pressure) machine. CPAP is the most common treatment for sleep apnea. A CPAP machine uses mild air pressure to keep your airway open while you sleep.
                
If your doctor thinks that you have sleep apnea, he or she may schedule a split-night sleep study. During the first half of the night, your sleep will be checked without a CPAP machine. This will show whether you have sleep apnea and how severe it is.
                
If the PSG shows that you have sleep apnea, youll use a CPAP machine during the second half of the split-night study. The staff at the sleep center will adjust the flow of air from the CPAP machine to find the setting that works best for you.
                
Home-Based Portable Monitor
                
Your doctor may recommend a home-based sleep test with a portable monitor. The portable monitor will record some of the same information as a PSG. For example, it may record:
                
The amount of oxygen in your blood
                
Air movement through your nose while you breathe
                
Your heart rate
                
Chest movements that show whether you're making an effort to breathe
                
A sleep specialist may use the results from a home-based sleep test to help diagnose sleep apnea. He or she also may use the results to decide whether you need a full PSG study in a sleep center.