24-Hour Rest-Activity Rhythms Linked to Rate of Biological Aging
Dr. Maher, Dr. Spira, and Chunyu Liu join the program to discuss new research linking daily activity–rest rhythms measured by wrist accelerometers to biological aging measured with epigenetic clocks. They explain circadian rhythms and the suprachiasmatic nucleus, describe the long-running Baltimore Epidemiologic Catchment Area cohort (mean age ~68) used in the study, and summarize key takeaways: stronger, regular sleep–wake and activity rhythms - along with exercise, healthy diet, maintaining a healthy BMI, avoiding heavy drinking and smoking, and stress reduction - are associated with healthier epigenetic aging. The researchers also highlight that this is an ongoing area of study and that future work may reveal targeted ways to influence specific genomic pathways.
Jeffrey Snyder, Broadcast Retirement Network
Dr. Maher, Dr. Spira, Chunyu. It's so great to see you.
Thanks for joining us on the program this morning.
Adam Spira, PhD., Johns Hopkins Bloomberg School of Public Health
Thanks for having us.
Jeffrey Snyder, Broadcast Retirement Network
And I'm real excited to talk about your study and the relationship between activity and rest and rhythm. We'll get then into that too in a minute, but Dr. Mayer, let me start with you. Um, I'm going to ask him a softball question here.
Uh, can we slow, have we figured out a way we meaning the medical community figured out a way to slow biological aging?
Brion Maher, PhD., Johns Hopkins Bloomberg School of Public Health
Uh, again, thanks for having us. One, one of the, among the things we know that there are multiple markers, including the, the ones we used in the study we're about to discuss, um, this, this example is methylation of specific changes in biology that happen over time as we age. And as you would expect, many studies have looked at correlational relationships between particular lifestyle factors, um, socioeconomic factors, medication usage, uh, and, and other environmental exposures and, and correlated those with, um, Differences in markers for biological aging and these markers for biological aging, aging are derived because they predict things like all cause mortality or something that is called health span.
And so among the things that we know impact the lifespan and health span, those tend to be correlated with, um, decreased biological aging. And so in theory, if you at any age change, change that your, uh, exposures or your dietary patterns or your lifestyle started exercising, quit smoking, quit heavy drinking, things like that, we would expect that you would see over time a decrease in biological age.
Jeffrey Snyder, Broadcast Retirement Network
So Dr. Spira, with that in mind, thank you for that. Dr. Mayer, let's talk about the study. Um, you know, I, I think the study and I'll let you kind of paraphrase it, but it really focused on activity rhythms and resting rhythms.
First. Let me ask you as a lay person, I'm not, I'm not a practitioner. I'm not a biotech gentleman person.
What, what, when we're talking about rhythms, what are we talking about here?
Adam Spira, PhD., Johns Hopkins Bloomberg School of Public Health
Thank you so much. Yeah, that's a great question. And I come to this research question really as a sleep researcher.
Uh, a lot of my work focuses on sleep and one of the things, and actually we have many different rhythms that our physiology sort of, um, uh, oscillates by, uh, on a roughly 24 hour basis. And so you've probably heard of the term circadian rhythms, right? And so many, many different aspects of our physiology follow a circadian rhythm, meaning they, they oscillate or fluctuate roughly once every 24 hours.
That comes from circa meaning approximately and diem being day. So we've got circadian. And the, the, uh, an example that is probably the most salient to most folks of a circadian rhythm is the alternation of wake and sleep, but many different, you know, uh, physiological processes like gene expression and hormone production and core body temperature also follow a circadian rhythm.
And what we were talking about in this study is, well, I'm going a bit deep here. So, you know, get me back on course. If I'm going to great, you're doing good, but, um, the, uh, circadian rhythms result from they're guided by the master clock in our brain, which is in the front of the hypothalamus.
And it's called the suprachiasmatic nucleus or SCN for short. And, uh, that part of our brain coordinates clocks throughout our bodies in all of our cells, uh, that oscillate according to the instructions of the master clock, uh, ideally, um, roughly 24 hours, uh, roughly once every 24 hours, um, following this, um, you know, this circadian pattern, even in the absence of any stimuli from the environment, like light, et cetera. That is the definition of circadian rhythm is something that follows a, uh, you know, a diurnal pattern that, um, is under the control of this clock.
And it happens endogenously without any input from the environment. What we did in this study was take a relatively distal measure of circadian function by looking at rest patterns of activity and rest measured at the wrist, uh, using accelerometers. Right.
We all are familiar these days with wearable devices. They're ubiquitous. We use research grade devices in this study to look at, um, to capture basically moment to moment changes in activity, uh, over a few 24 hour periods.
And what we're able to do with that is come up with basically curves on a daily, that over a daily basis that we can sort of, you know, average across people, uh, within people, and then compare people in terms of those curves. And we can get various measures from those curve, those data, including measures of rhythm strength or fragmentation, et cetera. And what we did in this study was look at the extent to which those different metrics that we can derive from those moment to moment measurements of activity versus rest.
Um, we get, you know, we looked at, uh, differences between people in those parameters in relation to their biological age as measured by these epigenetic clocks that Brian was referring to.
Jeffrey Snyder, Broadcast Retirement Network
So Chunyu, let's talk about the, the participants in the study, because you obviously need, I would imagine you need some level of human participation in order to, to, to do these measurements. Can you tell us the talk about the profile of those that participated in the study?
Chunyu Liu, Johns Hopkins Bloomberg School of Public Health
Yeah. So like we, uh, use, uh, Baltimore epidemiologic catchment area study. So like it is very long, uh, long cohort from like 1980s to now.
And we use a wave four, uh, wave five participants, which is like around recruited around like, uh, 2018. And, uh, uh, most of them are in their, uh, middle and older age. So the, the average age is around like 68.
And, uh, we have like, uh, like, uh, 50, around 50% males and females. And, uh, we have around like 80% white people, but we still have 20%, uh, like black people and there are still like, uh, a little bit number of the Hispanic and the, uh, uh, native, uh, like, like the Americans. So, yeah.
Jeffrey Snyder, Broadcast Retirement Network
So, so Dr. Spira, I mean, obviously it's a good poll. Why, why 68 year old, the average age of 68 year old could, wouldn't, wouldn't younger people have an impact on the study? Wouldn't that be maybe not predictive, but, but provide some data that would help maybe formulate, uh, maybe treatments in the, in the future, additional research?
Adam Spira, PhD., Johns Hopkins Bloomberg School of Public Health
That's a great question. Uh, and the thing is we have been following this sample since 1981.
Jeffrey Snyder, Broadcast Retirement Network
Okay.
Adam Spira, PhD., Johns Hopkins Bloomberg School of Public Health
These are people who have been part of a study, a very important study, actually, that provided some of the first evidence for the prevalence and one year incidence of mental disorders in the United States. So, um, and this dates back to, uh, Jimmy Carter and, uh, his commission on mental health, uh, and you know, that's a whole other, uh, interview, but it just goes to show you that you're looking, I guess you're actually looking, you're tracking these people over this long period of time, you need to do that.
Jeffrey Snyder, Broadcast Retirement Network
It's not like you can go back in time, you know, you, you have to, in order to test aging, you have to look at people as they age. Exactly.
Adam Spira, PhD., Johns Hopkins Bloomberg School of Public Health
And Brian and I, and our colleague, uh, Bill Eaton and some other, uh, faculty at Johns Hopkins and at the National Institute on Aging have been, uh, working with this population, uh, or with this, this cohort, um, now that they, it is primarily, uh, it's primarily older adults, right? Uh, we had some people who were in their, um, fifties, but I believe now they're all older than that. Uh, at least 60 and, um, you know, uh, we've been studying them and this was an opportunity, this is one of the many, many research questions that we can ask of this aging cohort, and we thought it was a great opportunity to ask this question because we had the monitoring data from the wrist, uh, accelerometry or actigraphy, and, um, we have this, uh, wonderful, uh, epigenetic aging data.
So that's why.
Jeffrey Snyder, Broadcast Retirement Network
So let me, let me, and I apologize, cause I only have a certain amount of time, but clearly we're going to, you know, this is an ongoing amount of research that we're going to have to continue to check the pulse of pun and fully intended, but Dr. Mayer, let me, let me come to you because we started with, can you slow biological aging? How do you take what you've learned from this study and can you apply it practically, like can Jeff Snyder take this information, go to his primary care physician yet, and then say, Jeff, you need to do this, this, this, this. And you're going to slow your butt.
You're not going to be 54 anymore. You're going to be 44. I mean, you know, what, what do we do with this data set and this research that you and the team have worked on together?
What's the next step?
Brion Maher, PhD., Johns Hopkins Bloomberg School of Public Health
Well, I think it's a very good question. And I think over the next decade or so, we'll, we'll understand more about this process. And if there are targeted approaches to improving, say in a personalized way, a person's epigenome, but as I mentioned, the, the general things we currently understand as improving health will have an impact on genome wide methylation and also site specific methylation in regions that are relevant to health.
And so my recommendation to anyone is that the exercise, eating well, maintaining a healthy BMI, those are the things that are, are most and, and obviously the maintaining a regular sleep pattern, which is, which is what our, which is what this work shows are things that are really important. Any, and also, you know, generally attempting to avoid stress or limit your responses to stress. Those are the kinds of things that there's pretty compelling evidence and impact your epigenome.
And like I said, over time, I think we'll understand better if there are ways that we can, you can target particular regions. I think one thing that's important to note is one of the reasons we do this kind of research is not just to say, Hey, there, there's this general impact on aging or there's this general in this direction or that direction is also for us to understand because these aren't anonymous regions in the genome that we're measuring. These are in genes.
And so we can understand the specific, specific biological pathways that are impacted related to sleep or impacted distressing related to stress exposures.
Jeffrey Snyder, Broadcast Retirement Network
Well, it's absolutely fascinating. As a lay person, those are things, I mean, I think you gave us good takeaways. There are things we can control.
There are a lot of things out of our control. We can't control the sun. We can't control our climate to a certain extent, but we can control certain things.
We need to take care of ourselves. And obviously the research will continue. Dr. Mayer, Dr. Spira, Chun-Yu, great to see you. Thanks for joining us. Great research. And look, we look forward to having you back on the program again, very soon.
Adam Spira, PhD., Johns Hopkins Bloomberg School of Public Health
Thanks, Jeff. Thanks for having us.
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This story was originally published May 23, 2026 at 7:30 AM.