From the Guidelines
The Multiple Wakefulness Test (MWT) is interpreted based on the ability of a patient to stay awake during four 20-40 minute test sessions, with a mean sleep latency of less than 8 minutes indicating excessive daytime sleepiness, as suggested by the American Academy of Sleep Medicine guidelines 1.
Key Parameters for Interpreting the MWT
- A mean sleep latency of less than 8 minutes is considered abnormal and indicates excessive daytime sleepiness.
- The presence of sleep episodes during the test is suggestive of severe sleepiness.
- For accurate interpretation, patients should have had adequate sleep (at least 6 hours) the night before testing, documented by polysomnography or actigraphy 1.
- Medications that affect sleep architecture, including stimulants, antidepressants, and sedatives, should be discontinued for at least two weeks prior to testing.
- Recent sleep deprivation, shift work, or other sleep disorders like obstructive sleep apnea should be ruled out or adequately treated before testing.
Clinical Considerations
- The test results should always be interpreted in the context of the patient's clinical history, as false positives and false negatives can occur.
- Repeat testing may be necessary if results are inconclusive or if the clinical suspicion remains high despite negative initial results.
- Actigraphy can be used to monitor total sleep time prior to testing with the MWT in adult and pediatric patients with suspected central disorders of hypersomnolence, as suggested by the American Academy of Sleep Medicine guidelines 1.
Important Considerations for Accurate Interpretation
- The MWT should be performed in a sleep-conducive environment, with the patient seated in a comfortable position and instructed to remain awake.
- The test should be conducted by a trained technician, and the results should be interpreted by a qualified healthcare professional.
- The MWT is a useful tool for assessing excessive daytime sleepiness, but it should be used in conjunction with other diagnostic tests and clinical evaluations to ensure accurate diagnosis and treatment of sleep disorders.
From the Research
Parameters for Interpreting the Multiple Wakefulness Test
The Multiple Wakefulness Test (MWT) is a 40-minute protocol consisting of four trials separated by 2-hour intervals, designed to test a patient's ability to stay awake 2, 3. The parameters for interpreting the MWT include:
- Mean sleep latency: the average time it takes for a patient to fall asleep during the test 2, 3
- Sleep onset REM periods (SOREMPs): the number of times a patient enters REM sleep during the test 2
- Clinical judgment: the sleep clinician's evaluation of the patient's ability to stay awake, taking into account the clinical history, compliance with treatment, and objective testing using the MWT 3
Indications for the MWT
The MWT may be indicated in:
- Assessment of individuals in whom the inability to remain awake constitutes a safety issue 2, 3
- Patients with narcolepsy or idiopathic hypersomnia to assess response to treatment with medications 2, 3
- Evaluation of residual excessive daytime sleepiness in obstructive sleep apnea patients adequately treated with nasal continuous positive airway pressure 4
Limitations of the MWT
There is little evidence linking mean sleep latency on the MWT with risk of accidents in real-world circumstances 2, 3. Therefore, the sleep clinician should not rely solely on mean sleep latency as a single indicator of impairment or risk for accidents, but should also rely on clinical judgment 3.
Protocol for the MWT
The American Academy of Sleep Medicine has published recommended protocols for the administration of the MWT, including guidance on patient preparation, medication and substance use, sleep before testing, test scheduling, optimum test conditions, and documentation 5.