Learn how Sleep Apnea is diagnosed through Polysomnography and home sleep tests. Understand the sensors used and how doctors calculate the severity of the condition.
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Diagnosis and Imaging
To diagnose Sleep Apnea Disorder, a doctor will evaluate your signs and symptoms and your sleep history. You may be referred to a sleep disorder center. There, a sleep specialist can help you decide on your need for further evaluation. The definitive diagnosis is usually made through a sleep study, also known as a Polysomnogram.
This evaluation often starts with a physical exam of your ears, mouth, and nose to look for extra tissue or abnormalities. The doctor may ask you to fill out a questionnaire, such as the Epworth Sleepiness Scale, to gauge how sleepy you feel during the day. This subjective data combined with objective testing provides a complete picture.
The primary examination for Sleep Apnea is the sleep study. A sleep study is a non invasive, overnight exam that allows doctors to monitor you while you sleep to see what is happening in your brain and body. For this test, you go to a sleep lab that is set up for overnight stays.
While you sleep, an EEG monitors your sleep stages and the cycles of REM and non REM sleep to ensure your sleep is not disrupted. It also measures things like eye movements, oxygen levels in your blood through a sensor, heart and breathing rates, snoring, and body movements.
During a Polysomnogram, you are hooked up to equipment that may look uncomfortable but generally does not prevent you from sleeping. Sensors are placed on your scalp, temples, chest, and legs. A belt is placed around your chest and abdomen to measure breathing effort.
A small clip is placed on your finger or ear to monitor the level of oxygen in your blood. A microphone records snoring activity. You sleep in a private room, and technicians monitor the data from a separate room. They can see if you stop breathing, how often you wake up, and if your heart rhythm changes.
For some patients, a Home Sleep Apnea Test is an option. These are simplified tests that you can do in the comfort of your own bed. They are generally used to diagnose Obstructive Sleep Apnea in people who have a high probability of having it and no other major medical conditions.
These portable kits measure heart rate, blood oxygen level, airflow, and breathing patterns. If your results are abnormal, your doctor might be able to prescribe a therapy without further testing. If the results are normal but you still have symptoms, a full in lab study might be needed.
The severity of Sleep Apnea is measured by the Apnea Hypopnea Index or AHI. An apnea is defined as a complete pause in breathing for at least 10 seconds. A hypopnea is a partial blockage of the airway that reduces airflow by at least 30 percent and causes oxygen levels to drop.
The AHI is the number of apneas and hypopneas recorded per hour of sleep. An AHI of less than 5 is considered normal. An AHI of 5 to 15 is mild Sleep Apnea. 15 to 30 is moderate, and an AHI greater than 30 is considered severe. This score dictates the urgency and type of treatment.
Another critical metric is the Oxygen Desaturation Index or ODI. This measures how many times per hour your blood oxygen levels drop by a certain degree from baseline. Normal blood oxygen saturation is usually around 95 to 100 percent.
In Sleep Apnea, levels can drop into the 80s or even lower. The frequency and depth of these drops correlate with the stress placed on the cardiovascular system. Severe desaturation is a strong predictor of complications like high blood pressure and heart arrhythmias.
In some cases, the doctor may need to see exactly where the obstruction is occurring. A Drug Induced Sleep Endoscopy involves sedating the patient to induce sleep while a thin flexible camera is passed through the nose into the throat. This allows the doctor to watch the airway collapse in real time.
Standard imaging like X rays or CT scans may be used to examine the skull and neck structure. These can reveal physical abnormalities like a recessed chin or a deviated septum. These are particularly useful if surgery is being considered as a treatment option.
The physical exam focuses on the upper airway. The doctor uses the Mallampati Score to assess the size of the tongue relative to the opening of the throat. You are asked to open your mouth and stick out your tongue.
A high Mallampati Score means the tongue obscures most of the throat, indicating a crowded airway. The doctor also checks neck circumference. A thick neck often indicates fatty tissue deposits that weigh down the airway when muscles relax during sleep.
The diagnostic process also involves ruling out other sleep disorders. Narcolepsy, for example, causes daytime sleepiness but has different brain wave patterns. Restless Legs Syndrome causes movement that disrupts sleep but is not a breathing disorder.
Medical conditions like thyroid problems or heart failure can also mimic Sleep Apnea symptoms. Blood tests might be ordered to check hormone levels. A thorough diagnosis ensures that the treatment targets the correct problem and not just a symptom.
Sleep Technologists are the professionals who conduct the sleep study. They are trained to place the sensors correctly and monitor the patient throughout the night. They do not interpret the results; that is the job of the sleep physician.
However, their observations are valuable. They note body position, noting if apnea is worse when on the back. They can intervene if a lead comes loose. Their detailed notes help the physician interpret the raw data from the sensors accurately.
Send us all your questions or requests, and our expert team will assist you.
A split night study is when the first half of the night is used to diagnose sleep apnea, and if it is severe enough, the technician starts CPAP treatment during the second half to find the right pressure.
No, home sleep tests primarily detect obstructive sleep apnea; they often miss central sleep apnea, restless leg syndrome, and other sleep disorders that require brain wave monitoring.
Normal oxygen levels are above 95%; levels dropping below 90% are concerning, and drops into the 80s or 70s put significant strain on the heart and brain.
You can search for “sleep apnea near me” to find accredited sleep centers, but you will usually need a referral from your primary care doctor to book a study.
It can be strange to sleep with wires attached to you, but most sensors are taped gently to the skin and do not cause pain; most patients sleep enough to get a diagnosis.
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