MSLT or MWT: Which Daytime Sleep Question Is Being Tested?
Sleep & NighttimeArticleFalling asleep and staying awake are different test goals.
A daytime sleep-test referral may use initials without explaining the question being asked. Start by asking the sleep team what the result is intended to help decide.
Compare the purpose
| Question | MSLT | MWT |
|---|---|---|
| What ability is measured? | Falling asleep during nap opportunities.1 | Staying awake.1 |
| What can it help assess? | Conditions such as narcolepsy or idiopathic hypersomnia, and some persistent sleepiness after sleep-apnea treatment.1 | Treatment response or alertness where staying awake matters for safety.1 |
| What should I ask first? | What diagnosis or symptom the team is investigating. | What decision the result will inform. |
Preparation is part of interpreting the result
The adult protocol recommends documenting sleep for two weeks before an MSLT with a diary and, when available, actigraphy. Ask the service which records it needs and how to complete them.2
Ask for a written medicine plan. Medicines and substances can affect testing, and any tapering needs clinician direction. If you use sleep-apnea treatment, confirm how to continue it before and during the test. Adequate sleep beforehand also matters.12
Keep preparation instructions beside the referral. If your schedule or medicine plan changes, contact the service to check what that means for the appointment.
Did I Do That in My Sleep? covers concerns such as snoring and night waking. See the book for its overview, and bring test-specific questions to your sleep team.
This article is for general educational purposes only and is not medical advice. It isn't a substitute for diagnosis or treatment from a qualified healthcare professional who knows your health history. Please don't ignore professional advice or delay getting care because of something you read here. If you think you may be having a medical emergency, call 911 or your local emergency number right away. Girl Playbook does not endorse any specific product, test, or provider.
Girl Playbook sells this book. It provides education and worksheets, not individualized medical care.
Sources
The research behind this article, in the order it’s cited. How we source our articles.
- American Academy of Sleep MedicineUpdated protocols available for evaluation of daytime sleepiness and alertness (opens in a new tab)abcdef
- Journal of Clinical Sleep MedicineRecommended protocols for the Multiple Sleep Latency Test and Maintenance of Wakefulness Test in adults (opens in a new tab)ab
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