What is a sleep study?
A sleep study helps doctors measure how much and how well a patient sleeps. It can identify sleep disorders like insomnia, obstructive sleep apnea (OSA), narcolepsy, restless leg syndrome, periodic limb movement disorder, and also behaviors such as sleepwalking. These disorders are not diagnosed with just a normal doctor’s visit. Your doctor must gather more detailed and conclusive evidence while you are sleeping not just awake. In addition to how much sleep you get, sleep study results will tell the doctor the quality of sleep you are getting and how much time you spend in different sleep stages. A sleep study is required for an obstructive sleep apnea diagnosis.
There are two types of sleep studies your doctor can recommend depending on which sleep disorder you may be at risk for. The most common type is a Polysomnogram (PSG), which is an in-lab study. The second kind is a Home Sleep Test (HST), which is performed in the comfort of your own home.
Polysomnogram (PSG) Sleep Study:
One type of sleep study is a polysomnogram. During a PSG sleep study, patients stay overnight in a sleep center with a sleep technician recording everything that is going on. You stay in a private room similar to a bedroom, located in a hospital or an outpatient facility. Before the sleep study begins, the sleep technician, who will be watching you on video from another room, will apply sensors and patches on your face, scalp, chest, fingers, and limbs, as well as belts around your abdomen and chest.
Each sensor that is on the body during the sleep study is responsible for recording bodily functions that will be used to determine whether there are abnormalities resulting in a sleep disorder.
Common measurements are:
- Respiratory airflow
- Snore volume
- Blood oxygen saturation
- Body position
- Respiratory effort
- Eye movement
- Electro-encephalogram (EEG) – measures electrical brain activity
- Electro-myograph (EMG) – measures electrical activity in muscles
- Electro-oculograph (EOG) – measures electrical activity associated with eye movement
- Electro- cardiogram (EKG) – measures heart rate and rhythm
Throughout the PSG, the sleep technician will channel the information being provided through the patches of sensors and belts, and prepare a report for your physician who will decide what diagnosis is necessary.
Home Sleep Test (HST):
Another sleep study is a Home Sleep test. An HST device is a portable sleep study. This study occurs in the comfort of your own bed. It can give your doctors detailed reports including much of the same information that a PSG sleep study provides. Recent technological advancements and subsequent changes in medical insurance policies have made home sleep studies a common method to consider. HST devices have as few as 2-3 sensors and as many as 20+ leads. (Though this depends on your disorder). Like the HST pictured above, some devices fit on the hand, or the head and others have patches that attach to the face, chest, and abdomen, much like a PSG.
Doctors recommend home sleep tests to patients with no major health issues. Major health issues are problems like cardiovascular disease, heart failure, stroke, etc. The most common use for an HST is to screen patients who snore or are at high risk for having obstructive sleep apnea.
How does a sleep study diagnose obstructive sleep apnea?
Apnea is an event in which a person stops breathing for 10 seconds or more. A hypopnea is a reduction in breathing causing a drop in blood-oxygen levels. The severity of your sleep apnea can be measured by the number of times you stopped or reduced breathing per hour.
Together, these events are counted in your sleep study results and known as the Apnea-Hypopnea Index (AHI). The AHI determines whether your OSA is mild, moderate or severe based on the severity classifications of OSA:
- Normal Limits: AHI less than 5 per hour
- Mild OSA: AHI between 6 and 15 per hour
- Moderate OSA: AHI between 16 and 30 per hour
- Severe OSA: AHI greater than 30 per hour
Find out if you should consider a PSG or HST for further evaluation.
Contact a Snoring Isn’t Sexy dentist if you snore and have these questions or concerns!