Anyone had a Multiple Sleep Latency Test (MSLT)?

After six weeks of using my newly prescribed CPAP machine (46/46 nights of 4+ hours, thank you very much!) I met with my sleep doctor to review the data. The good news is that my API is way down. The bad news is I'm still exhausted during the day. He recommend that I have another sleep study, followed by either a Multiple Sleep Latency Test or a Maintenance of Wakefulness Test (I can't remember which one) where I remain at the sleep lab all day following an overnight sleep study and take several naps, during which they record how quickly I enter REM sleep, etc. The doctor suspects that in addition to obstructive apnea, I may also suffer from narcolepsy. Has anyone else here had either of these tests? If so, how did it turn out? Are there other apnea/narcoleptic combos here and, if so, have you had any success treating your daytime sleepiness?

Here's a blurb on both tests:

Multiple Sleep Latency Test:
Also called a "Nap Test", the multiple sleep latency test (MSLT) is the standard way to quantify sleepiness and diagnose disorders of excessive sleepiness. An overnight diagnostic sleep test called a polysomnogram (PSG) is required the night prior to the daytime MSLT. After the PSG is complete, a series of nap tests are spread out over the following day. After being asked to try to fall asleep for each nap test, sensors on the head and chest record your brain wave activity, eye movements, muscle contractions and heart activity to accurately detect if you fall asleep. The information we collect during your study is reviewed and analyzed by our sleep specialists.

Maintenance of Wakefulness Test:
The Maintenance of Wakefulness Test (MWT) is a way to evaluate the ability to stay awake during the day. An overnight diagnostic sleep study called a polysomnogram (PSG) is usually required the night prior to the daytime MWT. After the PSG is complete, the MWT testing is spread over the following day. There are 4 tests spaced 2 hours apart. After being asked to stay awake, sensors on the head and chest record your brain wave activity, eye movements, muscle contractions, and heart activity to accurately detect if you fall asleep. The information we collect during your study is reviewed and analyzed by our sleep specialists.


Many thanks!

I know others here (not necessarily many tho') have done the test (I haven't), but I wonder a couple of things - like what if any symptoms of narcolepsy have you had besides sleepiness (that also goes with OSA)? And does your machine track data so we can see what's been going on? Too often doctors know the science of apnea, but get lost when it comes to equipment, how to use which, and how to read results (by read, I mean interpret your reaction to treatment). And have you had labwork recently to look at things like thyroid problems etc? AHI isn't everything... what about leak rates with your mask - are you confident you're not losing therapy air through your mouth when asleep?

I have had at least two MSLT tests, maybe three - memory is a bit foggy, had so many sleep studies.

Have you been on CPAP before or is this last six weeks the extent of your CPAP treatment? I think I saw in another thread that you are still struggling with mask issues. If this past six weeks is the extent of your CPAP experience, I don't think it is reasonable to expect to feel good yet. I commend you on using the machine every day - that truly is a big deal. It's just not enough to get you where you need and want to be. You are still in the adjustment phase, and will need to settle in to adequate quality treatment for a while to see how much it can help your daytime symptoms.

My personal - and non professional - opinion on the MSLT is except in cases of strongly suspected narcolepsy, the MSLT should be reserved until:
#1 OSA treatment is known to be therapeutic, consistent, and sustained yet without symptom relief,
#2 Hours of sleep (all on the machine) are adequate,
#3 All other medical conditions that can cause your symptoms have been formally ruled out, and
#4 All meds have been assessed for potential side effects that match your symptoms.

If you don't have narcolepsy, all the MSLT will be is a measurement of your sleepiness during the day, and hey, you already know you're sleepy, right? Now, if you were to be having episodes of cataplexy, hallucinations, or any overt symptoms of narcolepsy, then I could see going straight to the MSLT. But otherwise, if due diligence is not done first, you'll be in for a looooong day in the lab with unlikely chance of garnering helpful information. Been there, done that.

I have had several MSLT's & they are not hard, they will simply keep you up all night with sleep apnea test. Then they will keep you active, tell you to lay down at certain intervals & see how often you fall asleep. They also note any incidents of cataplexy. I've had many instances of falling asleep, but on the MSLT I had after getting my seizure 'cocktail' correctly calibrated, I had no incidents of cataplexy. That leaves my Dr. unsure that I have true Narcolepsy, but I do have incidents of falling asleep suddenly, so he is leaving the Narcolepsy diagnosis stand for now. The test isn't hard, just boring. After having the PSG the night before, you will be tired by the time you leave. I would recommend having someone drive you home afterwards, you probably won't want to drive afterwards, you may be too sleepy.

Hi everyone - thank you all for the great feedback. For some reason I didn't receive email notifications that your replies had posted, so I just saw them for the first time. I apologize for not acknowledging them sooner and, again, I really appreciate the input.

I had the MSLT Wednesday night through all day Thursday (yesterday). It was interesting on several fronts. First, I pretty much slept through the night, which is a new experience for me, since I've had two prior overnight sleep studies and slept terribly during those - especially once CPAP was introduced half way through the night. I'm not surprised that it was easier this time - first, because I knew what to expect; second, because this time I went into it with eight weeks of experience living with CPAP, whereas before, I had never used CPAP; and third, I was using CPAP from the get go, whereas during the previous studies, I would go to sleep without CPAP and then be awoken in the middle of the night to start it.

The MSLT portion of the test was, as predicted, rather boring but also frustrating. Even though I slept well during the night, I was still very tired during the day. What was frustrating was that I kept falling asleep, or wanting to fall asleep in between nap tests (which are scheduled every two hours) which they don't let you do, and then, when it finally came time for my scheduled nap, I had a hard time falling asleep. Before and after each nap they would have me fill out a form, asking how sleepy I was before the nap and then whether or not I thought I had slept and dreamt during the nap. My first nap was at 8 am and my last one was at 4 pm and other than the last nap, during which I definitely slept and dreamt, I wasn't sure whether or not I ever fell asleep. My experience was that I remained in a frustrated state of being awake and trying to fall asleep throughout the duration of each nap, but the tech told me - after filling out the questioner following each nap so as to not influence my answer - that I did in fact fall asleep during each nap. The other frustrating aspect, other than wanting to sleep in between naps, was that when they woke me up from each nap, I felt that I was just on the verge of sleep and wanted to be allowed to do so! Unfortunately, thems not the rules, so on went the lights.

As for being "active" in between naps, that actually wasn't the case for me. I pretty much stayed in or on the bed all day, reading, watching a little TV, eating/snacking, etc. I Ieft the sleep lab feeling pretty wiped out (as jencat824 predicted), went to a friend's house and took a nap (how ironic). I'm supposed to see the doctor in about 10 days to go over the results, but I'm feeling a bit impatient, so I'm thinking of calling them and asking if he can just go over the results with me over the phone sooner. Either way, as soon as I get the results, I'll post them here.

As for other symptoms of narcolepsy, such as cataplexy, I don't believe I have any. As for other causes of my daytime fatigue and sleepiness, meds are not the cause, as the symptoms are there just the same whether I'm on meds or not. None of the other health issues I suffer from seem to be the cause, either. All my adult life (I just turned 50) I've felt this way and it was always attributed to things like the Epstein-Bar virus or chronic fatigue - at least until I was diagnosed with sleep apnea - the first time 10 years ago, when my insurance wouldn't cover CPAP so I didn't follow through with treatment. Now the doctor feels that there may be more going on than just Apnea. Even though I've only been using CPAP for eight weeks, and during that time I have, in fact, struggled a bit with masks, he felt that I should have been feeling better by now, thus the MSLT. So we'll see what the study tells us and go from there.

If you've lost lots of therapy air out your mouth every night while using a nasal mask, you won't feel better (of course). Can you try some FF masks, or at least a chinstrap or taping for a few nights to see if things improve?

Thanks for the input. I actually haven't had any issues with air leaking from my mouth. When I use nasal pillows, I get a leak rate of 0. When I use a nasal or full face mask, the leak rates are higher, but only because of poor sealing, due mostly to my mustache and beard or simply a poor fit.