Here at we receive a LOT of emails from people looking for sleep apnea treatments. Some of those people suspect they have sleep apnea and are gathering information on treatments; others have had apnea for years and have already tried a range of treatments (mostly unsuccessfully).

What do both groups have in common? MOST do not know the underlying cause of their sleep apnea.

Knowing exactly what’s causing your sleep apnea is extremely important. Just like a mechanic needs to find out what’s causing that clunking sound in your car before he can figure out how to fix it, YOU need to know what’s causing your apnea before knowing what an appropriate treatment is.

What are the common causes of obstructive sleep apnea? Generally speaking, the “cessation of breath” that characterizes sleep apnea is caused by a blockage in the upper airway. That blockage usually comes about from too much fatty or flabby tissue in the throat, or from a nasal blockage.

Here’s a partial list of the causes of sleep apnea:

  • Obesity (which leads to excess fatty tissue in the upper airway)
  • Old age (which leads to the tissue in the upper airway becoming flabby)
  • Deviated septum
  • Enlarged tonsils or adenoids
  • Tongue, soft palate, or uvula is too large
  • Jaw is too small

You probably have a few questions at this point:

  1. Can I self-evaluate my sleep apnea? How do I do it?
  2. I’ve heard that the two main ways of diagnosing sleep apnea are (a) staying overnight at sleep study center, or (b) do a home sleep study (home testing for sleep apnea). Which is better for me?
  3. Are there any online tests for sleep apnea? Which are the best ones?

Great questions 😉 This article will answer all of those questions!

The STOP-BANG Survey: first step for self-evaluation

Self-evaluation is one of the simplest and most convenient ways to know if you have sleep apnea. Assuming that you’re eventually going to see a doctor, the STOP-BANG survey is a great first step. The best part is that it can be done from the comfort of your home and ensures 100% privacy.

Here are the four yes-or-no “STOP” questions which need to be answered for diagnosing sleep apnea:

S: Is your snoring sound really loud (i.e. is it louder than the sound of talking or even heard through closed doors)?

T: This is to measure tiredness and daytime sleepiness. Do these feelings overpower you often?

O: This is for observation of your condition by others. Has anyone noticed your restless sleep and breathlessness during sleep?

P: This question is related to your blood pressure. Is your blood pressure high and do you take any medicine for your condition?

If you have said ‘yes’ to two or more of these questions, chances are high that you have sleep apnea. You need to talk to a sleep doctor.

Further confirmation regarding your condition is available when you answer the BANG questions, which are as follows:

B: Is your BMI (Body Mass Index) more than 35 kg/m2?

A: Over you over the age of 50?

N: If your neck circumference more than 40 cm?

G: What is your gender? (Males are more likely to have sleep apnea.)

This self-evaluation is aimed to prepare you better to meet the sleep specialist, who might also use the answers to these questions to diagnose your case more accurately.  But you also have to remember that your unique medical history is also going to provide valuable guidelines to the doctor for initiating the best therapy for you, in case you have sleep apnea.

Sleep Study Center or Home Sleep Study: Which one should you opt for?

How is sleep apnea diagnosed? While there are several types of sleep apnea tests that are done, the ultimate choice of the type of test depends on the type of symptoms you show. The tests that are normally done are:


Polysomnogram or PSG

Multiple Sleep Latency Test, or MSLT

Maintenance of wakefulness test, or MWT.

If the doctor suspects that the symptoms could be due to circadian rhythm disorder, you might be advised another type of test called Actigraphy.

Polysomnography is one of the most common diagnostic tests considered to be most objective way to assess the severity of the condition as well as type of sleep disorder a patient could be suffering from.

The test measures a wide range of physiological and biological parameters including brain waves, muscle tension, eye movement, respiration, oxygen level in the blood and sound monitoring (for snoring, gasping, etc.) during sleep. With so many parameters tested, it is obvious that a large amount of data is also generated by the test.

The various parameters tested are:

  • Brain waves by electroencephalogram (EEG)
  • Eye movements by electro-oculogram (EOG)
  • Muscle tension and movements by electromyogram (EMG)
  • Oral and nasal air flow
  • Chest and abdominal movements
  • Loudness of  snoring
  • Oxygen levels in the blood using oxymetry

Over and above video recording the total time that you are sleeping, this test can also record seizures, sleep walking or talking, and other parasomnia behaviors.

Polysomnography can be done both at night or during the day and at home or a sleep center. People who find it difficult to fall asleep at night usually opt for daytime sleep test.

Why and when does one choose to do sleep study at home? There are essentially three driving factors for this decision: cost is less; lack of appropriate facilities or good sleep centers nearby; the patient is too ill to travel to the sleep center.

Whatever may be your personal decision regarding choice of venue for doing a sleep study, you should have more details about both these options and know what to expect from these alternatives.

Sleep study center: Fundamentals

large showroom with every variety of sleep apnea machineThere are three categories of sleep study centers:

  1. Attached to a hospital
  2. Affiliated to an University
  3. Private ownership

The first criterion for selecting a sleep center is to check its accreditation to American Academy of Sleep Medicine or AASM. This will guarantee quality service and premium professional expertise. These accredited centers also use high-quality materials during the study.

Are sleep centers and sleep laboratories same? While both can be accredited to AASM, a sleep laboratory primarily focuses on breathing-related sleep disorders like sleep apnea. Sleep centers on the other hand, run diagnostic tests for all the other types of sleep disorders.

[content_box_blue width=”75%”]Why should you look for AASM-accredited sleep centers?

  • The medical director of a center, who is the overall in-charge of service quality as well as patient care, would be a doctor who is a state license holder.
  • The doctors are board certified in sleep medicine.
  • Accommodation ensures privacy, comfort and security.
  • Regular staff training keeps the employees updated in terms of medical knowledge and services.
  • Fee structure follows state and federal regulations.
  • Operational guidelines are as per American Medical Association’s Code of Medical Ethics.

The best way to find such an accredited sleep center is to visit AASM website – that has a easy-to-use center locator along with all the information you might need.[/content_box_blue]

 Home sleep study: fundamentals

A home sleep study is carried out with the help of a portable monitoring kit. The kit consists of a monitoring system that does not require a great amount of space. The kit also contains, recording device, sensors, belts and other relevant accessories. The operating system is the same between sleep study at home and at a center in terms of fitting sensors, recording data, etc.

It is worthwhile to know that sensors are linked to a number of ‘channels’ to record data from various parts of the body. The more number of channels there are, the more data there will be. While a home study kit usually have between one and seven channels, a sleep center will use 12 or more. Thus, a sleep center is equipped to diagnose more types of sleep disorders whereas home sleep study can usually detect only one – and mostly sleep apnea.

Depending on what your doctor advises, you could opt for the most common type of diagnostic kit that uses four to seven channels and measures nasal and oral airflow, breathing effort, oxygen levels in the blood and heart rate.

Though home sleep studies have their own limitations, there are many who believe that the quality and reliability of the results that emerge from such tests are comparable to that obtained from overnight sleep study performed at sleep centers.

How is the data processed and when do I get to see the results?

The test results will reveal the following:

  • The time you took to fall asleep and wake up again
  • Stages of your sleep
  • Whether you had abnormal breathing during sleep
  • Oxygen levels in your blood
  • Type of body movements while you were asleep.

After the test is over, the sleep technologist finishes the scoring of the sleep stages, etc and collates all the data collected. An independent review of the readings is also done by a sleep physician who ultimately decides on the interpretation of the results. You would then be called for a personal discussion about the outcome of the study. Since the test involves studying several parameters, it is not before 2 weeks that you can expect a written report of the test. However, the final diagnosis of your condition is made only after comparing your medical and sleep histories with the results obtained.

What do the results of other tests show?

Multiple Sleep Latency Test: This test, according to AASM is the de facto standard for the objective measurement of sleepiness. This test records how long you take to reach the REM stage of your sleep, which if it is less than 5 minutes show that you might be affected by a sleep disorder. It is useful for diagnosing narcolepsy.

Maintenance of wakefulness test (MWT): the results of this test clarifies whether the degree of sleepiness can impair personal safety of the individual.

Can I interpret the sleep study results myself?

Yes you can, provided you are familiar with certain terms that are used in the report. The two terms that you need to understand as they will tell you how severe your sleep apnea is:

  1. The Apnea Hypopnea Index (AHI) and
  2. Oxygen desaturation levels

The apnea-hypopnea index, or AHI is expressed as a number, which is a combination of the values of apneas (pauses in breathing) and hypopneas (numbers of shallow breathing episodes) per hour of sleep. It denotes severity of the condition. For example:

None/Minimal: AHI < 5 per hour

Mild: AHI ≥ 5, but < 15 per hour

Moderate: AHI ≥ 15, but < 30 per hour

Severe: AHI ≥ 30 per hour

In case you come across the Respiratory Disturbance Index (RDI) in your report, remember that RDI not only includes apneas and hypopneas but also more faint signals given by breathing irregularities. This obviously means that your RDI can always be higher than your AHI.[/gn_box]

Oxygen Desaturation: what it means

Sleep apnea causes major oxygen deprivation in the blood, the normal level (saturation) of which is between 96 and 97%. When the level goes below 90% the condition is mild; between 80 and 89% moderate and when the levels go below 80% the condition is serious.

What is the biggest benefit of diagnosing sleep apnea?

Undiagnosed and untreated sleep apnea entails major health complications many of which can turn fatal. But if one is knowledgeable about the likely symptoms, causes and risk factors that trigger onset of the condition then he or she can always ask the treating doctor for a sleep apnea test, to confirm the state of his or her health. This is the only way one can prevent further deterioration of the condition.

For example, if you are obese, above 50 years of age, drink alcohol excessively or snore loudly and persistently because of deviated septum blocking the nasal passage, you can always get yourself diagnosed for sleep apnea.

Is online diagnosis of sleep apnea possible? If yes, which is the best site? is one of the best online resources dedicated to educating apnea patients. Their online sleep test is simple, easy and quick and takes about 5 minutes to complete. After completing the online test, you also get a chance to get the results reviewed by a board-certified sleep doctor for which you do not have to pay anything. You can also get a free consultation appointment with a sleep doctor in your area.

Another good resource is, which offers an online test that utilizes the Berlin Questionnaire and Epworth Sleepiness Scale. Click here to take the sleep apnea test.

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