What Is a Sleep Study?
A sleep study is designed to determine whether a person who exhibits certain symptoms during sleeping — and waking — hours has a treatable condition, or even if a condition exists during the night that can be causing problems in the daytime.
Therefore, it’s important to look at potential causes and symptoms in a person’s life that may warrant a sleep study:
. Snoring at night
. Sleepiness, or fatigue, in the daytime
. Reports of breathing interruptions while sleeping
. Insomnia (inability to sleep)
. Narcolepsy (sudden onset of sleep)
. Restless legs (a syndrome that causes uncomfortable leg sensations)
A sleep evaluation often is done at a sleep center, where you must go for the night and undergo various medical tests while asleep. Other sleep evaluations can be done at home, but we’ll cover those in another article.
At the sleep center, you’ll be fitted with small attachable pods, or electrodes, on your head and body for some of the tests, similar in experience to undergoing an EKG (or electrocardiogram), which is also done with electrodes. Pulse oximetry, measuring the oxygen level in the blood vessels, will be carried out through a finger attachment, while an air-flow monitor will be applied to your face to measure breathing.
The electrodes will accomplish four tests: 1) an EEG (electroencephalogram) to measure brain wave activity, 2) an EOG (electrooculogram) to measure eye movement, an EMG (electromyelogram) to measure muscle movement,and 4) an EKG, already mentioned, to capture electrical activity in the heart.
Overall, a sleep evaluation is often called a polysomnogram, which may also be accompanied by multiple sleep latency tests (MSLTs) and multiple wake tests (MWTs). MSLTs measure how long it takes to fall asleep, while MWTs measure whether you can stay awake during specified times.
There are no known side effects to a sleep test, and a trained sleep technician is present all night to make sure everything goes well.
Overall, a sleep test will measure:
. Sleep latency: the time it takes to fall asleep
. Sleep duration: the period of time a person stays asleep
. Sleep efficiency: the ratio of the total time asleep to the total time in bed
. Breathing patterns: the number and depth of respirations
. Eye movement: the number of eye movements and their frequency or speed
. Brain activity: the electrical currents of the brain
. Limb movement: the number and intensity of movements
. Heart rhythm. the electrical activity of the heart
. Oxygen saturation: the percentage of oxygen in the blood
. Acid/base balance of the stomach: the amount of acid secreted during sleep
Armed with all these measurements, the sleep phsycians and professionals can make an informed evaluation of your problems (if any) and help chart a course of action to get your condition under control and relieve your symptoms.