Millions of people worldwide suffer from sleep disorders, including sleep apnea, insomnia, narcolepsy, and restless leg syndrome, among others. In order to diagnose these common ailments, doctors may require the patient to undergo a sleep disorder test, which is typically performed overnight at a sleep disorder clinic. During a sleep disorder test, measurements are taken to categorize the stages of sleep and detect any sleep irregularities. The information from a sleep disorder test is interpreted by a trained physician who will then make a determination whether a sleep disorder exists or not.
A sleep disorder test may include polysomnograms, which are often referred to as rapid eye movement studies, and multiple sleep latency tests. When undergoing these tests, the patient must be monitored by a sleep technician. The patient is generally required to arrive to the study about two hours before his typical bed time, and is asked to refrain from drinking beverages with alcohol or caffeine for a certain amount of time before the study in order to get an accurate reading.
Before the patient goes to sleep, electrodes are temporarily attached to his chin and head, and above the eyelids. The electrodes pick up electrical signals produced by the brain, and also aid to record muscle activity. The information is then transmitted through wires and logged throughout the sleep disorder test on strips of paper.
During the overnight study, tests also monitor a person’s state of sleep. These states include rapid-eye movement and non-rapid eye movement, which are measured with electromyogram and electro-oculogram machines. A person with healthy sleep patterns typically alternates between the two sleep patterns every 90 minutes and has about five cycles of rapid-eye movement and non-rapid eye movement nightly. Other things that are monitored during the sleep study include how long it takes a patient to fall asleep and the amount of time it takes for rapid eye movement to occur.
A person’s heart rate and breathing also are closely monitored during the sleep disorder test with an electrocardiogram machine. A sleep technician will observe a patient to record any variations to his respiration or heart rate. Typically, a person with a sleep disorder, especially sleep apnea, will have instances where he momentarily stops breathing while sleeping. The number and length of such episodes are recorded.
A multiple sleep latency test is typically performed in sleep labs after a sleep disorder test for people suspected of having narcolepsy. This test is done in the morning and determines the amount of time it takes for a person to nod off during the day. With the test, a person takes several naps at regular intervals. A person with narcolepsy will typically fall asleep during the day in under five minutes.