Welcome to Straight Talk on Health. I’m Chet Zelasko. Recent health headlines have suggested that taking naps every day can cause cardiovascular disease. Now, you know that with that kind of headline I’ve got to find what's going on behind it. But let me start with a story:
About 16 years ago, Well, if I'm going to be precise, it was 16 years ago, my wife Paula and I spend several weeks over the course of an entire year helping our son Matthew build his shop down near Charleston, South Carolina. So when we were down there the daily routine when something like this: Start early in the day before the heat built up. Break for lunch. Then take a 30 to 45-minute rest or nap then work the rest of the day. The thing is that I've used that approach off and on ever since. Back then it was to avoid working during the hottest hours of the day. Now it's just something that I found to be beneficial.
Recently, a couple of studies were published that called into question whether naps were a good idea as they might be related to cardiovascular disease. So, of course, I have to check that out. And one of the reasons that this research news caught my attention was because the last time I wrote a research paper about sleep, which is just in 2019, and napping, it showed that there was no relationship between napping and cardiovascular disease. In fact, in a study published in ‘Heart’ in 2019, which is the study that was talking about, this was over 3,000 subjects. They were from Switzerland. And what they found is that those people that regularly took a nap the over a five-year period of follow-up. There was a 42% decrease in cardiovascular disease events like heart attacks or strokes when a person took a nap one to 2 times per week, then with no risk if a person napped every day. So because there was no risk, that seems to indicate, even if you took a nap every day, that there's no relationship because one of the things that they did in that Swiss study is they didn't allow anybody in who already had a diagnosis of any type of cardiovascular disease. Or any type of major risk factor. Major risk factors would be moderately high blood pressure, moderately high…I think they've changed the nomenclature, but moderately high would be something like over 120, but less than 130 over 80, but less than 90. So it should be below 120 over 80 and you’re start to creep up there. So, they didn’t allow any of that in this study.
What's the difference between that and the most recent research? Well, in the most recent research, there appeared to be a relationship between napping and hypertension. And in another study napping and cardiovascular disease, in those two studies, and they contained thousands of subjects. Why the difference? We're going to get into that, why there were different results a little later. But let me just say this; this is one of those scenarios where I think people get frustrated with research because just like this; one study says one thing and another comes along with completely different conclusions. Now, I hope that if you've been listening long enough, you won't be in that group.
In this case, why might studies that seems similar on the surface come up with different results? So we're going to take a look at the studies and I’m going to give you the citations for the paper very quickly. One was the Journal of the American Heart Association in 2022, we’ll call it the Swedish study. In this case they looked at over 20,000 pairs of twins that began being tracked way back between 1958 and 1962. The second study is in the journal, Hypertension in 2022. We'll call that the hypertension study. But it also used the United Kingdom Biobank. Now, the Biobank is a large study where they're collecting all kinds of data on over a half a million people in the United Kingdom. Now, the advantage that those 3 countries have - Switzerland, Sweden and in the United Kingdom is that they have excellent electronic medical records so that if someone is diagnosed, you know it. That way they can keep track of any events that happened to them. And that's part of socialized medicine because people move around it’s and easier to carry the records with him because it's all electronic, not an indictment of what we do here in the United States. But let me tell you, it is nice to have access to your electronic medical records because oftentimes I see the results what test that I've had done before the physician even has a chance to comment. Why? Because it's just me looking at my results. They may have a dozen people, maybe more a day that they've got a look at the results for. So I like that part of it.
Well, while the studies seem to ask the same question, the studies were actually quite different. In the Swedish study that showed a reduction in cardiovascular disease event for napping 1 to 2 times per week. The subjects were selected, as I mentioned earlier because they did not have any cardiac events or any diagnosis of cardiovascular disease. That means that any current events, disease that took place in the follow-up period was a primary event. In the other 2 studies, high-risk cardiovascular disease events were excluded in one, but not the other certain types of cardiovascular disease risk factors were permitted. As I mentioned, the moderately high hypertension.
Second, the purpose of the Sweden study was designed to look at the development of cardiovascular disease because if you're looking at nap time, you're looking at many, many other variables as well. What other factors could be related to the development of cardiovascular disease. The other 2 studies, which are from Switzerland and the United Kingdom, as I said, recruited over half a million subjects. But the research questions appeared to be decided after the studies began. Now, there's nothing wrong with that. I've been involved with large group of data where people asked a group of us to look at data that had already been collected. But especially when there are questionnaires, the questions have to really fit that you asked of the people, how many hours do you nap a day? whatever the case may be, those have to completely coincide with the research questions you are asking. And if it doesn't, then the data that you're looking at may not be worth words printed.
Not saying there's anything wrong with what they did, but that's going on more and more because, look, there's a study, all of us, I’m a part of that one here in the United States they’re looking to get 1 million volunteers. And so that's a large data bank, which anybody can request the data on. It’s all anonymous. And when you sign up for the study, you signed up for that part of it so that they can analyze it and see risk factors for cardiovascular disease. I know that we're going to get genetic testing results. I know that I am in that genetic bank of people that can’t stand cilantro. Tastes like Soap. There happens to be a gene for believe it or not. I have that gene which is why I don't like it.
To get back to the point, all of the questions that were used in queries about sleep and about napping, half the match research questions that you asked. So, for example, the premise was that daytime napping causes cardiovascular disease and hypertension. Let's look at it this way. It seems likely that those conditions could cause fatigue, which would require daytime napping. But even if that were not the case, the subjects appeared 2 already have issues with sleeping like sleep apnea, which could impact hormone levels that contribute to cardiovascular disease, such as cortisol levels and many, many other things. So what can be gained from this? These large studies attempted to make sense out of prior research from 20, 30 years ago that showed some form of link between daytime napping and cardiovascular disease.
What I think these studies demonstrate is that the cause of the nap is important. If it's a planned nap, designed to allow digestion or pause in the long work day, it may not be hazardous to your health. And I can assure you that the relative heart disease risk does not change. But I can tell you that the benefits that I got, even though it may take if taken me 19 minutes to actually fall asleep and my alarm would go in the 20th minute, it’s like Bliss, real bliss, because what happened is I felt refresh in that time. But that's a planned nap.
Now, if a person doesn't sleep well or has sleep apnea and is fatigued because of that, being forced to nap during the day to recover may indicate a higher risk of developing cardiovascular disease and hypertension. So, it's not just the simple as sleep itself. Diet, body mass, lack of exercise, and many other factors all have a role to play in sleep quality and cardiovascular disease as well.
But here's the thing. If you plan your nap, you're in control. If you are forced to nap, it's time to look at your lifestyle and see what else you can change. And that's what I have to say about sleep and napping. And unfortunately, that's all the time I have for this show until next time, this is Dr. Chet Zelasko saying health is a choice, people, choose wisely today and every day.
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Narrator: Straight Talk on Health with Dr. Chet Zelasko was recorded in the studios of WGVU Public Radio in Grand Rapids, Michigan. The views and opinions expressed on Straight Talk on Health are not necessarily those of WGVU, its underwriters, or Grand Valley State University. Episodes are found at wgvunews.org and wherever you get your podcasts, please rate and subscribe.
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