A sleep study — or polysomnogram (PSG) — is a multiple-component test that electronically transmits and records specific physical activities while you sleep. The recordings become data that are analyzed by a qualified doctor to determine whether or not you have a sleep disorder.
The four types of polysomnographic studies are:
- Diagnostic overnight PSG — This is the general monitoring of sleep architecture (such as the amount of NREM and REM sleep, number of arousals) and a variety of body functions during sleep, including breathing patterns, heart rhythms, and limb movements. It is usually indicated in the evaluation of sleep-related breathing disorders or abnormal movements during sleep.
- Diagnostic daytime multiple sleep latency test (MSLT)— This test is used to diagnose narcolepsy and to measure the degree of daytime sleepiness. To ensure accurate results, it is performed on the morning following a diagnostic overnight PSG.
- Two-night evaluation PSG and CPAP titration — CPAP(continuous positive airway pressure) is a sleep apnea treatment that involves the delivery of air into airways through a specially designed nasal mask. On the first night of the two-night protocol, general monitoring, and diagnostic evaluation are conducted. If sleep apnea is discovered, the patient returns for a second night to determine the necessary CPAP pressure required to alleviate apnea.
- Split-night PSG with CPAP titration — Split night PSG is conducted when moderate or severe sleep apnea has been discovered or strongly suspected during the first part of the night’s study. The second half of the night is used for CPAP titration.
HOME SLEEP TESTS
.In some cases, your doctor may provide you with simplified tests to be used at home to diagnose sleep apnea. These tests usually involve measuring your heart rate, blood oxygen level, airflow and breathing patterns. If you have sleep apnea, the test results will show drops in your oxygen level during apneas and subsequent rises with awakenings. If the results are abnormal, your doctor may be able to prescribe a therapy without further testing. Portable monitoring devices don’t detect all cases of sleep apnea, so your doctor may still recommend polysomnography even if your initial results are normal.