The Truth About Sleep Studies: Home Versus Lab Tests and Their Role in Diagnosis

Welcome back to the Hidden Sleep Disorder Show! In this episode, we’re joined by Dr. Vishal Saini to unravel the mysteries behind sleep studies, from what really happens during an overnight test at a sleep center to how modern home-based tests work and their limitations. Whether you’ve been referred for a sleep study, had confusing results, or are simply curious about why sleep disorders so often fly under the radar, this conversation will help you understand the science, technology, and critical decision-making behind diagnosing hidden sleep issues. We’ll break down the differences between at-home and in-lab sleep tests, discuss the role of daytime nap studies, and offer practical advice on what your test results do (and don’t) reveal about your health. If you or someone you know struggles with unexplained exhaustion or poor sleep, grab a notebook - this episode will empower you to get the answers you need.

Timestamps:

00:00 Understanding sleep studies

06:15 Traditional home sleep test setup

07:58 Using sleep rings for apnea detection

13:01 Insurance impact on sleep apnea testing

16:58 Importance of overnight sleep study

20:15 Understanding medical test limitations

23:25 Ruling out sleep apnea first

27:10 Sleep study and test insights

28:32 Concerns about home sleep tests

31:50 Upcoming episodes preview

Dr. Vishal Saini - https://www.mwcsd.com/dr-vishal-saini/

Show Website - https://the-hidden-sleep-disorders-sho.beam.ly/

Podcast Producer - https://tophealth.care/

“Disclaimer: Informational only. Not medical advice. Consult your doctor for guidance.”

Transcript

SPEAKER_00 0:00

When a person is sleeping or they're deep in sleep, they don't really know what exactly is going on. They're waking up and then they're trying to figure out in the hindsight that maybe that's what happened. Sometimes we have bed partners that are reporting those symptoms that we are completely unaware of. And you could have a person who's rocking the whole house, but they don't hear their own snoring. The sleep study, that's generally a broad term to get some signals, get some data to look deeper into my sleep. And this could be only a few physiological signals, for example, my oxygen, my heart rate, or it could be almost 18, 19, or 20 different physiological signals from the in-lab sleep study. So we'll break all that down as we go.

SPEAKER_01 1:19

Over the past few episodes, we've talked about narcolepsy, idiopathic hypersomnia, and why so many sleep disorders go undiagnosed for years. And I think one thing that really keeps coming up in those conversations is sleep testing and specifically what it actually involves. A lot of people have been referred for a sleep study or have already had one done, but still really aren't sure what the results truly mean. So today we're going to answer that question directly. Dr. Saney, it's nice to see you as always. I'm excited for this episode. I know you brought in a few things to show us and really walk us through in more depth about what sleep studies are. So I'm excited to hop into this with you today.

SPEAKER_00 1:56

Yes, I'm excited too. Happy to be here. You know, I I was driving my motorcycle today, so I was thinking, let's dedicate this episode to all the drivers who are in sync and know and aware of drowsy driving and the risks for you know that are involved with drowsy driving. So this episode is for all the drowsy drivers in the world.

SPEAKER_01 2:20

Absolutely no, that's such a good dedication and a big topic to address because I know it affects so many people. And so let's just dive in because I know when people hear the word sleep study, even myself included, prior to learning so much from you, they kind of picture something complicated or intimidating. But let's break it down. So, in the most simple terms, what actually is a sleep study and why do doctors order them?

SPEAKER_00 2:44

So, sleep study is a generally broad term for various different tests out there. Now, obviously, when a person is sleeping or they're deep in sleep, they don't really know what exactly is going on. Either they're waking up and then they're trying to figure out in the hindsight that maybe that's what happened. Sometimes we have bed partners that are reporting those symptoms that we are completely unaware of. And you could have a person who's rocking the whole house, but they don't hear their own snoring. So they don't even know. In fact, a lot of people stay in denial because of that. So the sleep study, and we'll break down further as to what those different kinds of sleep studies are, but that's generally a broad term to get some signals, get some data to look deeper into my sleep, and this could be only a few physiological signals, for example, my oxygen, my heart rate, or it could be almost 18, 19, or 20 different physiological signals from the in-lab sleep study. So we'll break all that down as we go on in this episode.

SPEAKER_01 3:59

And then so with sleep studies and sleep tests, there seem to be so many different kinds. So some are done at home and some are done in the lab. So can you walk us through the main types and explain what makes them different?

SPEAKER_00 4:12

Yes, and that's a big distinction. These are the two broad categories. Now, back in the day, there wasn't any home sleep testing. All the sleep testing was done in a sleep lab, in the hospital, or an independent facility where you would spend a night there in the sleep lab, and that's where we're recording the all the signals that we need. So that's in-lab sleep study. And of course, there are different kinds of sleep studies that are taking place even inside the sleep lab. But then as the technology evolved, we moved on to doing a lot of this testing at home, and so we label those as home sleep testing. And of course, even the home sleep testing has evolved and it has exploded into several different kinds of home sleep tests that are out there. So those are two major distinctions, and we'll look at each one of those individually as we go forward.

SPEAKER_01 5:13

And speaking about the home sleep tests, so I feel like they've become a lot more common over the last years or in more recent years. So, what can a home sleep test really tell us and where does it fall short when it comes to maybe diagnosing some of the more hidden sleep disorders?

SPEAKER_00 5:29

So before I answer that, let's look at different kinds of home sleep tests. And I have two versions here with me. So this is the more sort of modern version of a home sleep test. And it's basically a ring that I'm gonna be putting on my finger as I sleep through the night. So, what this one is recording is my blood flow through the finger and my oxygen data, and it's trying to figure out what are the changes happening in my blood flow as my breathing is changing through the night. So that's one example of a home sleep test. You know, how intimidating is that, right? It's pretty straightforward. Then the other one is this little bit more with it has more signals. So this one, more traditional home sleep test that we are used to, and this one goes on a belt, and you know, you put a belt around your chest, and then it has this pulse rope that you put on your finger through the night. Now, additional to what the ring was doing, it has this nasal cannula that kind of sits in my nostrils. You've seen people wearing oxygen, right? They use a nasocannula. So this is the same nasal cannula, but it's not delivering any oxygen. What it's recording here is the airflow through my nose, and it's trying to record some snoring as well. So it has, you know, a couple additional signals, so to speak, compared to the ring devices. And there are two different kinds of ring devices out there these days. One, so for example, this is I think Sleep Image, B LAN comes to my mind. Those are the two different ones. There's watchpad, that's another popular one that's out there. And the watchpad kind of goes on my wrist, and then it has a little probe that goes on my finger, and that's also trying to record changes in my blood flow pressure to kind of see, because it changes each time I snore, it changes, I quit breathing. So those are the main kinds of home sleep tests that are out there. So then what are these things trying to understand? And how do they know I have sleep apnea, right? So that's the main question here. So the way these rings work is they're trying to couple my heart rate variation or changes with my snoring, with my drop in oxygen levels, with my sort of activity or muscle activity in my sleep, and then you put all that data together to figure out okay, how many times this person might be quitting breathing. And because it's a very limited sort of channel that is driving all that information from, and that's a big limitation for these. Obviously, this is a super convenient test, right? Versus having to deal with you know multiple wires, sleeping in a different sleep environment. This is much easier to accomplish, but you have to know the limitation that it's not gonna give you as much detail on your sleep. And then a lot of these signals are were driving a lot of the data indirectly just based on the changes in my blood flow or my oxygen levels off of the finger. So there could be a lot of false positives, there could be a lot of false negatives. So just because your finger test or the ring study shows a negative or comes back normal, that may not capture everything that we're looking for, and then hence the need for more detailed sleep studies as well.

SPEAKER_01 9:26

Yeah, it definitely seems I can see how it would be a lot more convenient, but in a way limiting. But for those patients who do need an in-lab study, the overnight experience can feel somewhat you know like a mystery. Like what exactly is it and what's going on? So, what actually happens from the time a patient arrives at the sleep center to the time that they leave in the next morning?

SPEAKER_00 9:47

Yes, let's break down that mystery because there shouldn't be any mystery around it. There's nothing hidden there. So as you walk into the sleep lab, generally sleep techs will greet you and then they check you in, show you your room. And generally these rooms are private rooms, they're set up like a hotel, as in our sleep lab, and you have your own bed generally. So we have queen size beds in our sleep lab, and we have, you know, it's set up just like a hotel. So all you got a picture is a hotel room. There's TV, you have your own bathroom, you have a recliner, you know, stuff to sort of uh wind down and and feel comfortable. Now, in the in-lab sleep study, first thing the tech after they check you in and you know you change and you're ready, they'll put electrodes or stickers at different parts of my body because that's what we're trying to record. So I have an example of what exactly the in-lab sleep study is doing. This is the box that the sleep techs use, and this is where these little holes is where the electrodes, their leads get inserted, and then the stickers on my face. So as you can see, it shows a picture of a scalp or head. So they're putting some electrodes on my head, on my scalp. There are electrodes close to my eyes to record my eye motion, and that's how we can tell if someone is going through RAM sleep or not, because RAM, which stands for rapid eye movement, you can only detect that if you're actually recording eye movement, right? If I'm not even recording eye movements, how do I know that I'm really in RAM sleep, right? So that's that's where the RAM sleep came from because we were recording their eye motion or eye movements when they were sleeping. And then, of course, there are channels like EEG channels where it's recording my cardiac activity or heart rate activity. There are EMG channels here, which is recording my muscle activity. So as you can see, there are close to 16, and then there are three additional channels that sometimes we use depending on if we're dealing with some other complex sleep problem. But generally, basic 16 are on this box. So that's a lot of physiological signals that we're capturing compared to this one that's only capturing, you know, one or two at the most, right? So that's the main difference, and that is what your sleep clinician or your sleep lab is trying to determine that okay, which test is most appropriate for you? And then obviously I will have more faith in the in-lab sleep study just because I'm going through a lot more data. So even if my home sleep test shows negative or doesn't really show a whole lot, or for example, our hypersomnia patients, right? They're sleepy, and all this thing is talking about is sleep apnea, even though I'm not even looking for sleep apnea. So then how is this going to be helpful to understand my problem, right?

SPEAKER_01 12:55

So would you say that that's maybe like a first step for a lot of people?

SPEAKER_00 12:58

A home sleep test? Yes. Actually, that's a valid point. Let me take you a little bit in in the backstory of this, okay? Because like everything in medicine, this started out as a very well-intentioned tool, but now because of all the I don't know if I I should call it it's almost like apathy from insurance companies sometimes, where now you're almost forced to use this, whether this is relevant to my patient or not, because the insurance policy is that, hey, we're only going to pay for the home sleep test first, then you rule out sleep apnea from that, which is not even a good test to rule out sleep apnea. It's a good test to rule in, but only for patients who are at high risk for sleep apnea. For patients, like for example, you're a young woman, you're at low risk for sleep apnea. Just from that fact that I'm less than 30 years old, my sleep apnea risk is pretty low, then home sleep test is not the right test for you because it's gonna miss out on sleep apnea if the risk, the baseline risk for sleep apnea is low. So you have to know the limitation of the test device that you are using, and that is true for all the sleep clinicians. They should know what the limitation of their home sleep testing devices are so that they can have a backup plan to see, okay, this one didn't really answer us, then what's the next step? And they should be able to answer that question to their patients.

SPEAKER_01 14:36

So then once the sensors are recording throughout the night, what specific information are sleep specialists analyzing specifically? And beyond that, are there any patterns or what patterns are finding the most significant?

SPEAKER_00 14:50

So, based on my clinical sort of suspicion, right? So, for example, let's say I have a patient who's in their mid-40s, 50s, they're male, they have a history of high blood pressure, their bed partner tells them that they're snoring, they're tired, they may have diabetes, they may have some obesity, BMI may be 30 or higher. So their risk for sleep apnea is already quite high. And that person would make a good candidate to start out with a home sleep test, because it can easily detect the sleep apnea in a high-risk individual. But in contrast, I have a skinny person, they don't sleep so good, or they wake up feeling tired, they have no history of snoring, or no one ever told them that they snore, then this test is going to be very limited in providing me much answers. Now they may still have to go through some home sleep testing if that's what their insurance plan requires them to do. So sometimes even patients are puzzled by that. It's like, okay, you're talking all about hypersomnia, but then why are you ordering this home test? And that is to make my patient qualify for the real test that they actually need by ruling out sleep apnea based off of the home sleep test. You know, so I think that goes back to our discussion where we said, okay, hey, just because your test came back normal, especially if it was a home test, don't bet your life on that.

SPEAKER_01 16:25

That makes sense. Almost like kind of first step, pro like process of elimination sort of thing. And then we're talking about these sleep studies, which are usually night sleep studies, but we've previously mentioned the MSLT, which is a daytime nap study. So in previous episodes, we've talked about that. So for the listeners who may have not heard or listened to those episodes yet, which you should go listen to those episodes, but if they haven't, can you explain what that is and why it's done after the overnight study and what it really reveals that the overnight tests cannot reveal alone?

SPEAKER_00 16:58

Absolutely. So think of it this way: if I'm trying to determine how sleepy this person is during the daytime, then just by looking at my nighttime sleep is not gonna give me the whole picture. So the overnight portion of the nap study is to one document how many hours of sleep I got going into the nap study. Because as we talked about it, if I'm sleep deprived or I didn't sleep for enough hours going into the nap study, then it makes it challenging to analyze and come with some good conclusions. Because sleep deprivation can cause false positive on the nap study. So then when that happens, then you lose confidence in the nap study. So that's why the overnight test is to increase that confidence. And one, and sure, you you get enough sleep the previous night. And two, is also because some sleep disorders like sleep apnea are gonna show up when I'm sleeping for long hours at nighttime, or I may have other sleep disorders where I'm sleepwalking or I'm jumping out of bed or I'm acting out on my dreams. So a lot of those sleep disorders, we don't want to miss them by not doing the nighttime portion. So that's what the nighttime portion is to help us achieve those. And then the next day, generally, if we were not doing a nap study in the morning, you wake up, you go home. But for the nap study, you stay in the sleep lab, and after you've been awake for about two hours or so, then that's when we start to begin the nap study and ask the individual that, okay, let's try to take a nap. We'll give you 20 minutes to fall asleep. And what we're really looking for is that, hey, even though this person slept for seven, eight hours the previous night, they're still sleepy. And how quickly they can fall asleep on those naps, that's exactly what we're looking for. To see as soon as they hit the first sleep onset, that's what we're recording. The second piece of the nap studies we're recording if your brain enters into any abnormal sleep pattern, and that's one way to, you know, that's why we have those eye channels I was just showing on the amplifier, where we're recording that, okay, if your eyes start to move really quickly as soon as you fell asleep during that nap, that tells us that I'm going into my RAM sleep, and which is not really normal for an adult brain to go into RAM sleep that fast. So if my brain is going into RAM sleep that quickly, that tells me there is some pathology that I should be looking for. So those are some of the signs that I'm trying to find on the NAB study or MSLT, which stands for multiple sleep latency test.

SPEAKER_01 19:59

Interesting. And I know many people listening have probably been through a sleep study and may have been told that their results were normal, but they're still feeling exhausted every day. So we've talked about this a little bit before, but how is that possible and what should those patients do next?

SPEAKER_00 20:15

So just like any test in medicine, Leila, every test, whether it's a blood test, whether it's imaging, whether it's uh cardiology test, stress test, whatever, right? Every test has its own set of limitations. Every test has false positives, every test has false negatives, and so we have to be aware what those limitations are for the testing that we are doing. So, for example, if I run a home sleep test on an individual that is low risk for sleep apnea, then chances are it's going to come back negative. So then that tells me that I'm missing some of these, because there are plenty of skinny people running around with terrible amounts of sleep apnea, which can be easily missed. So that's where you need confirmation test to prove that it's truly negative. Then the second piece, for example, even the in-lab sleep study, even though it's considered gold standard, it still has its own set of limitations. For example, we have patients who come to the sleep lab, but then they find it really hard to sleep just because of how many data we're collecting. There are plenty of electrodes, they're sleeping in a strange bed, they might be nervous that, oh my gosh, someone is looking at me, which is truly, really not that true. But you know, obviously we're recording the signals and looking at the signals and making sure we're capturing good quality data, but still, there are plenty of reasons to be nervous if you've never done this before. So that could impact my sleep, right? So then I may not end up sleeping as much. So, for example, I was in the sleep lab, for example. Hours, but I only slept for let's say two hours, then we don't have much data, right? So then either I bring you back to the sleep lab or we do a multiple nights of home sleep test at home to sort of gather more information. So those are you know the main set of limitations that we run into. You were talking about nap study, even that has limitations. Sometimes I get extremely sleepy people, but for whatever reason they get super anxious or nervous and they can't fall asleep during those naps. So some sort of performance anxiety, I think, where oh my gosh, but they're extremely sleepy. And then when you repeat that nap study a few months later, it might be able to show some positive stuff. So that's why you can't just live or die by the outcome of the test. You have to talk to the individual in front of you who's undergoing these tests and to realize, okay, why am I testing this patient? What would be the best test for this person? And how will I use that information to make their life and sleep better?

SPEAKER_01 23:08

Absolutely. And then, so not everyone who is tired needs a full in-lab polysomnogram, right? So, what symptoms or situations should prompt someone to specifically really ask their doctor for a comprehensive sleep study rather than the at-home test?

SPEAKER_00 23:25

That's a pretty good question. So let's break it down a little bit. Most of the times, sleep clinicians will rule out sleep apnea first, regardless of what symptom you present them with. And the reason is because that is the most common sleep disorder out there. So we have to rule that out because without treating that or getting sleep apnea out of the way, it's extremely hard for us to see a clear picture. So now if a person is tired or sleepy, and whether they have any risk factors for sleep apnea, just the fact that they are sleepy and tired, I will still rule out sleep apnea for them and make sure that's not causing or contributing to those symptoms. Now, if they don't have sleep apnea, that's great that I move on. But if we do end up finding sleep apnea, even when it's mild, we tend to treat it and get that out of the way to see is it going to make a difference in their fatigue, in their tiredness, in their sleepiness? And a lot of the times the answer is yes, it does. But the lot of the times the answer is no, it doesn't, and then we move on to more detailed testing. So that's how you have to sort of look at it in an approach where think of it as a step approach where we're taking baby steps to get to the right answer. And there are people who we find out they have sleep apnea, we treat their sleep apnea, they have terrible sleep apnea, but their spiness does not get better because they have other hidden sleep disorders that we need to unmask. And that's what this further testing will come into play from there.

SPEAKER_01 25:09

And from there, for example, once the study is complete and the results are ready, what should patients really expect from the results conversation? And then what are the most important questions that they should be asking their doctor when they get those results?

SPEAKER_00 25:23

So when we go over the results, especially, for example, let's say home sleep test, I would suggest, because a lot of people will just assume that, okay, home sleep test is negative, it should be good. So then really ask them, hey, can I do multiple nights of home sleep tests if that's an option? And generally, when I say multiple nights, I'm not talking about seven, ten nights. Usually, even two nights is good enough to capture some night-to-night variation. And we very commonly, in fact, as a general rule, we do two nights of home sleep tests for majority of our patients, okay? And that generally will help us. You could call it first night jitters or whatever. Sometimes, you know, that takes care of that problem. So that's number one. Number two, when you are looking at the results, you don't just look at the sleep apnea number, you look at the oxygen numbers as well. What was my lowest oxygen? How frequently these oxygen levels were dropping. Some of these newer ones now, they've started to also report what we call hypoxic burden. And what basically is a fancy way of saying what is the percentage of time that your body is living at low oxygen levels, meaning below 88%, as a percentage. So for example, if my hypoxic burden is let's say 20%, what that really is telling me is that 20% of the time every hour I sleep, my oxygen is running low, and that's not good for my body, for my brain, for my mood, for my heart. So that's another indicator that I may be dealing with some sleep disorder breathing. Now it's pretty interesting that your sleep apnea number, which is AHI or apnea hypopnea index, that's just one number. So just because my AHI is normal, my hypoxic burden might still be quite high, and that's where it will require for further follow-up testing in the sleep lab to confirm those findings. So that's one of the things to look for. The other thing is, especially if I have a lot of sleep fragmentation or I have insomnia, I have difficulty staying asleep, and that is something that the home test is not going to be really good at helping you figure out because that's where we need all those brain channels, brain EEG channels, to help us understand, okay, why is the brain waking up? Is it waking up in response to dip in my oxygen? Is it waking up because my heart starts to race? Is it waking up just without any reason and is just in habit of waking up from chronic insomnia, from PTSD, from nightmares, whatever the case may be. So those are some of the more detailed nuances that you can look into if you have those detailed channels from the in-lapse sleep study. So that's how you would, you know, sort of go through the sleep reports with the providers. Because, you know, in this day and age, the home sleep testing has gotten so popular that every random person is offering these home sleep tests, whether they know anything about that test or not. So there's a lot of you know, players on the market. If you Google home sleep tests, you'll probably come across the whole page full of different providers. But that doesn't really mean they know what they're doing. It might just be a testing shipping company that's doing these tests, or even medical supply company, you know, where hey, they just want to sell you their equipment, so they're happy to run tests on you, but they don't really know what to do if the test comes back negative, or if the test comes back extremely bad, they're just gonna be selling you their equipment. So you have to be very cautious because there are plenty of players on the market that are trying to take advantage of sort of let's just call it sleep boom, or you know, people worried about their sleep.

SPEAKER_01 29:31

Absolutely. And it's it's funny because like you said, I had never even really heard of a sleep study until somewhat recently, and now I I have been hearing about it more and more.

SPEAKER_00 29:40

Yeah, it's everywhere. You it's probably showing up on everybody's social media feeds, you know?

SPEAKER_01 29:46

Yeah, I saw it in a TV show, and I think after that it's like, and now obviously working with you, I my my ears perk up every time I hear one, but it has definitely, I think, become, like we talked about, way more common and popular. And uh, we broke down so many different things today about sleep studies. But are there any other final thoughts or anything you wanted to add in to this episode?

SPEAKER_00 30:06

So what I would say to close this is that sleep studies or sleep testing is just one of the tools that a sleep clinician will use to gather data, to get a big picture, to get some details that obviously we can't see because you're not sleeping in the sleep lab every day. You're sleeping at your own place. So then how do we gather that information that is relevant? But you still have to put it into perspective and make sense. And also there are limitations. So that's really what is the bottom line that we need to be careful when selecting these tests and also be hopeful and be aware that there is just not one test. There are several other tests. There's follow-up tests, there are tests to confirm findings, and to kind of come up with a good solution, good answer for my sleep disorders.

SPEAKER_01 31:08

Absolutely. And like I said, today we broke down really what sleep studies actually involve from home sleep tests to in-lab polysomograms and daytime nap testing and why the right kind of testing is so essential for identifying the hidden sleep disorders that we cover on the show and understanding what these tests really measure and what they can miss is an important step for anyone who's ever been struggling with unexplained fatigue and hasn't yet found clear answers. So, for anyone listening, if you found this conversation helpful, make sure that you are following the show. Be sure to follow and share so you don't miss any future episodes. And thank you all for listening to the Hidden Sleep Disorder Show. It's always a pleasure speaking with you. I can't wait to talk to you again soon. We have another few good episodes planned. So can't wait to chat soon.

SPEAKER_00 31:54

Thank you, Layla.