When sleep deprivation is suspected, your doctor will want to order a sleep study to test for apnea or other sleep disorders.
The sleep study takes a comprehensive look at your sleep dynamics. Some of the things it measures are how long it takes you to get to sleep, how many times you wake during the night, the quality of your sleep, and blood oxygen levels during sleep.
There are three common types of sleep studies:
Multiple Sleep Latency Test (MSLT) – There are two versions of this test. The daytime one tests for narcolepsy by measuring the degree of sleepiness during the daytime. The nighttime test measures how long it takes for someone to fall asleep.
Multiple Wake Test (MWT) – Measures if you can stay awake during normal activities when a person would be expected to remain awake.
Polysomnogram (PSG) – This is general evaluation and monitoring. There are two versions. One version is a two night test. The first night includes monitoring of sleep activities.
The second night is to find proper corrections for problems found on the first night. The second type of PSG is the split night.
The first half of the test is monitoring and recording, the second half is finding proper corrections especially during a sleep study for apnea.
Sleep studies look for the severity of apnea events. How long they last and how often they happen are important to assess. Airflow drops are considered apnea events. 5-15 apnea events an hour is considered mild sleep apnea. Moderate sleep apnea is 15-30 events an hour. Severe apnea is 30 or more an hour.
The other way to diagnose the severity of sleep apnea involves assessing when sleepiness occurs and how often. This method is accurate, but subjective to provided information.
Brain waves are measured during a sleep study for apnea. There are four different types recorded during the study – alpha, beta, delta, and theta. Each one represents a different sleep stage. The study will measure the amount of time spent in each stage of sleep.
A typical nights sleep will include a progression through the four different stages of sleep, then 60-90 minutes of REM sleep. This cycle is normally repeated around four times a night. Any deviation in this cycle can result in sleep deprivation issues.
Blood pressure, pulse and respiration rates are recorded. It is not unusual to see blood pressure spikes as high as 220/130 during a sleep study for apnea.
As an apneic event happen and the blood vessels constrict, the heart will race and cause pounding against the narrowed vessels thus increasing blood pressure.
After breathing resumes, respirations are increased in an effort to restore normal oxygen levels. This can have a devastating effect on overall health if it continuously happens over a period of time.
Sleep tests are crucial when sleep disorders such as sleep apnea are suspected. They will record valuable information that will be used in diagnosis and treatment plans.
The tests are performed by trained sleep technicians and the results are read by an experienced doctor specializing in sleep disorders.
Sleep studies for apnea may include same night treatment for severe cases. This is one test you will want to make every effort not to miss.