| Multiple Sleep Latency Test | |
|---|---|
| ICD-9-CM | 89.18 |
| OPS-301 code | 1-795 |
| Minutes | Sleepiness |
|---|---|
| 0–5 | Severe |
| 5–10 | Troublesome |
| 10–15 | Manageable |
| 15–20 | Excellent |
The Multiple Sleep Latency Test (MSLT) is a sleep disorder diagnostic tool. It is used to measure the time elapsed from the start of a daytime nap period to the first signs of sleep, called sleep latency. The test is based on the idea that the sleepier people are, the faster they will fall asleep.
The MSLT is used to test for central disorders of hypersomnolence such as narcolepsy or idiopathic hypersomnia, or to distinguish between physical tiredness and true excessive daytime sleepiness. Its main purpose is to discover how readily a person will fall asleep in a conducive setting, how consistent or variable this is, and whether there are abnormalities in the rapidity of REM sleep onset. This can be used to identify and differentiate between various sleep problems.
The test consists of four or five 20-minute nap opportunities set two hours apart, often following an overnight sleep study. During the test, data such as the patient's brain waves, EEG, muscle activity, and eye movements are monitored and recorded. The entire test normally takes about 7 hours during the course of a day.