The Decibel - Why a sleep doctor says we should never change our clocks again

Episode Date: October 31, 2025

On Sunday, most Canadians gain an hour of sleep as the clocks get turned back to standard time. But while most of us have gotten used to the bi-annual time change, our bodies have not. And with a growing number of experts saying the practice messes with our sleep – should Canadians stop messing with the clock?Today, psychology professor Joseph De Koninck is here. He studies sleep at the University of Ottawa, and his recent research looks at how Daylight Savings Time impacts our circadian rhythms, what we can do to minimize the health effects the change has, and why he thinks Canada should consider staying on Standard Time year-round.Questions? Comments? Ideas? Email us at [e-mail] Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

This Sunday, most of Canada will gain an hour back as we switch from daylight saving time to standard time. And while we've gotten used to changing the clocks back and forth, especially with our smart devices, mostly doing it for us now, our bodies have not. Changing our time by an hour can have a huge impact on our health. Today, psychology professor Joseph DeConeck is here. He studies sleep at the University of Ottawa, and his recent research looks at how daylight saving time affects our circadian rhythms, what we can do to minimize negative consequences, and why he thinks Canada should consider staying on standard time year-round. I'm Cheryl Sutherland, and this is the decibel from the Globe and Mail.

Professor Joseph DeConink, thanks so much for being on the show today. Oh, it's my pleasure. So most of Canada has been observing daylight saving time for over a century now. But before we get into what we've learned about that time change in recent years, I want to talk about what we've learned more generally about sleep and how important it is to our well-being. So how much does sleep or a lack of it affect us? Well, the sleep is the common denominator for psychological and physical adaptation.

In other words, if you don't get the proper amount, of sleep or the good sleep, nothing works in terms of physical, also in terms of functioning psychologically, mentally. And we know that sleep deprivation is a suicidality factor because you lose your judgment. You see, the important thing is that our brain is really, really complex. It's been really developed. The frontal part of our brain is crucial, consciousness, creativity, all of this, the perception of reality, the perception of emotions and things like that. This part of the brain is extremely calorie using. We have a lot of cells that need to recover because we've been used all day.

And so when you lose sleep or when you get the end of the day, your judgment is not good at all. And if it's in the long run that you don't sleep well, then you have a host of diseases that you can develop. up because the immune system is rejuvenated during sleep. Almost every month now, we discover that some of our major health illness are related somewhat to sleep. The last one was Alzheimer's disease. Oh, wow. So it's essential.

We know that. When we don't sleep well, it doesn't work well. Yeah. And so the big issue is that modern society is creating so many things now that interfere with sleep. So you have light all the time. We have night work. We have iPhones now that really take away, typically half an hour of sleep, and so on. So there's a host of issues that we have now to learn, where they're learning to deal with them.

And part of that, of course, is daylight saving time. That definitely impacts how we sleep. And on Sunday, most of Canada will be falling back, which means we'll be back to standard time, which means, at least some of us believe this is an extra hour of sleep, since, for example, ADM becomes 7 a.m. So people are generally excited about this time change, but is this actually something to be celebrated? Oh, I think so.

Oh. I think it's like going back to normal. Yeah, tell me more about that. Well, it's just that humans have evolved as day people, as light people. I mean, we function in light. And the idea is that we evolved in the equator with 12 hours of light, 12 hours of darkness. But humans have gone up to the north and adapted to that.

So now we're up to fairly high above the equator, especially in Canada, which is a kind of issues, which means now that we are only eight hours of light during the winter, during December and so, the winter months, but we do have in the summer the counterpart is 16 hours of light. So that's quite an elastic for our biological clock that is supposed to readapt because it requires light. And so the idea is that because we function here, now with the amount of light that we get, the biological clock uses the first light in the morning. And the midday light, our brain records this and decides, okay, we're going to distribute our activity, digestion, everything that we do, respecting this situation.

So what essentially what we're doing with so-called daylight saving time is that we're playing with that biological clock, and we're playing with that. Yeah, so let me talk to you about that because what you said here is very fascinating, because you're saying that there is something to be celebrated when it comes to the changes happening on Sunday, because we're going back to standard time, and that aligns us with the solar time, which is our biological clocks. But then there's, of course, the change that happens in spring, which definitely feels harder because it's generally viewed as losing an hour of sleep. And we're going into what is called daylight saving time.

Can you explain why it feels worse? And what does it do to us? Oh, the interesting thing here is that, for example, we talk about daylight saving time. So let's start with the real culprit here for the general public. Daylight saving time would mean that we're saving daylight time. We're not saving daylight. We don't get more daylight saving time. We're moving it towards the evening.

That's all. So the sun rises later in the morning. Yes, okay. The spring change has two major issues. The first one is that we lose an hour of sleep. And since most people now, we know about 50% of Canadians, have issues with sleep or are sleep deprived somewhat. So when we move to the clock,

then the second thing is that we desynchronize or a biological clock with the light, okay? So we tend to go to bed later. So throughout the summer, we tend to sleep less significantly, half an hour. So losing an hour of sleep as a significant effect. It's not like losing four or five hours, but it's still there. It's still well documented. So it is just an hour, and it only really affects us for a week, per se, sometimes, you know,

to adjust to this time change. Is it really a big deal then? Humans, as I said, are really well organized to adapt to different situations. You know, we have people living in the North now, you know, the First Nations, the First Nations. They live with only a few hours of light during the winter, and they adapt, they adapt, you know. But it takes a long time to adapt. So here what we're doing is we're doing a yo-yo every six, six months. just one hour is enough to affect your mood, then it has an impact somewhat on, for example,

your appetite, you tend to eat more because the hormones regulate the food intake or the need to food or you become hungry. It's all regulated in sleep, in deep sleep. So if you chip away some of it, it will have an effect, and it have more of an effect on vulnerable people. You know, we talk a lot that very well documented that there are more heart attacks following, you know, on the Monday, Tuesday after the change. And car accidents as well, I hear about too, right? Yes, yes. But it all happens to people who are at the edge already, okay? Elderly people like me, kids are really more affected as well.

So outside of the abrupt hour change, it's that we're getting less sleep, that whole time. we're on daylight savings time because we're just staying up later but generally getting up at the same time. And, you know, and kids go to, don't want to go to sleep because it's still light out there. I know this from actual life. Yeah. My daughter will tell me it's light outside. I don't need to go to bed. Yeah, that's right. So fortunately for the kids, you know, have school, you know, at least for the two months or two months of the summer, there's a problem that when comes September because then we have to have to readapt and they can't get that morning sleep. I can say from experience that the spring time change feels worse as I get older, both physically and mentally.

Is there any truth of this? Is the switch harder as we age? Oh, yes. Biological clock is aging as we get older. Just to give you a good example, as where it's sleep, my area of expertise. You know, what really is. puts up to sleep is the lack of light, but it's also body temperature, and it goes down. If you're well synchronized, you know, around 9 o'clock, it's the temperature going down that puts you to sleep with the lack of light. So when you get to sleep, it goes down until 4 or 5 o'clock in the morning, so you really get it to deep sleep.

And then after that, it starts to rise. Well, what happens when you get older is that curve of temperature flattens. And that's why elderly people wake up all the time because their temperature doesn't go up enough and doesn't go down enough. It's normal. Another sign of aging, I guess. Yes. Time changes bad on me because I'm getting older. And that's just part of life. Joseph, I want to ask you a bit more about light, because you've written that light in the

morning up until noon is especially important for us. Can you explain why that is? Yes, because the biological clock works with a... There's a center in the brain that is really responding to light and that synchronizes the whole system of a clock and it goes all over the body, even in all the cells we have this clock system. It's very precise. People, you know, can, I realize myself now that you can wake up just at this particular

minute, you know, and some people are able to do that. That's been demonstrated before. Yeah. So our brain is really well equipped. You know, it's much better than an iPhone. And it can just perceive time and of all kinds. So this comes through the eyes, the light, and it goes through the retina. And then there are receptors there that connect directly. Okay. So that's how it happens. And this is particularly important in the morning because our biological clock is more than 24 hours. So every day, It has to readjust by one or two or three minutes. Otherwise, you will tend to go to sleep later and later. So a lot of us, you know, because of these issues of that, we tend to have a phase delay. We tend to go to bed later and later and later and later.

Okay. So we need to have the light early in the morning. Depression is often an issue also of that synchronization. And so the best non-medicated way, to contribute to a treatment of depression is morning light. It's not evening, it's morning light, even though we say, oh, we're very happy to have more light in the afternoon. But for depression, it's a morning light that starts the car.

So that is why it's so crucial not to move this morning light towards the evening. So that's the argument that basically, you know, this time change we're doing right now, to standard time. That's why we need that, because we need that morning light. Whereas right now in the morning, it's so dark, but in fact, going back to standard time is helping us to kind of realign and re-center. Yeah, I was just looking again now to the times. Like, for example, in Toronto, you know, right now, it's about, the sunrise is about a quarter to eight. So if we were to go on without going back one hour, by the end of December, we would be. be at the quarter to nine, the sun would rise.

Can you imagine that? That's really late. So that's why we can't have daylight saving all year around. But next Monday, you will see that because we're going back, the sun will rise at seven. So all these people are now at 7 o'clock on the road, and they're going to be very happy because they will have that. On the other end, when they go back from work in the car, it's going to be dark. It's so sad.

Okay. Yeah. So, but you have to decide where it is. So, you know, a lot of people will say to me, you know, I don't care because I wake up at 9 in the morning. Yes, because you don't have to work or, you know, you work. Or you don't have little kids. Yeah.

So science is saying if you go to daylight saving time year on, you're going to be sorry. We'll be right back. So, Joseph, you've laid out how daylight saving time can negatively impact our well-being. The time change was widely introduced in Canada in the early 1900s to get people working longer and to save energy during the First World War. But of course, the war is over. And now all this research shows it's hurting our health. So why are we still doing it?

Well, there is quite a bit of lobby from the business that is, and it's why, I have nothing again. this business, that a profit from the light in the golf, in the U.S., particularly, you know, they want to golf all year around, like in Florida. So they want to have more light in the evening. This time, the convenience store in Ontario, have lobbied. But there's another issue that I want to mention is that standard time is normally aligned, you know, the time zones are normally aligned. with the solar time. But that's not what happened in Canada as much. In Canada, we have adjusted

because we're so widely spread, we've adjusted it to economy. So the big cities like Toronto, Montreal, Ottawa, we're all well in the time zone. But for example, we've put Quebec and Ontario in the same time zone. So at the both ends, they're in the wrong thing. So they have these issues where, for example, in Tunter Bay, if we were to go to daylight saving, the light would come up only at 9, 30, 10 o'clock. So it sounds like with even with time zones, and also with daylight saving time and switching the clocks back and forth, that the economy is capitalism that is actually kind of pushing us. It's not about our well-being here. It's this economic part of it that is actually pushing us to do these changes. Yes. And, you know, for example, Ontario and Quebec,

I always say, where we want to go to daylight saving, well, you try it, but they say only if New York and Michigan and I mean, you know, because of the... Stock exchange? Yeah, yeah, because people say, you know, it has to be closed at 5 o'clock, so we have to have the same time because, you know, people do the trading and so on. So we can't, we have to manage, but that's not the case because a lot of people, a lot of other countries and so follow that. And they just adapt, apparently, the business. So it's a difficult issue for politicians, and we're trying to provide them with more information. So some Canadian politicians do want to do something about this time change. But instead of moving to standard time, they want to make daylight savings time the permanent time.

So what would that do if we went on to daylight saving time permanently? People will regret it. It's very clear now that we've been in touch with politicians now. So what they're trying to do now, federally, is to consult and then arrive at consensus. The issue, again, would be that ideally you'd want to, if you want to go to daylight saving, you'd have to completely readjust the time zones because, as I've mentioned, it exacerbates certain areas. The sun won't start until way later in the morning.

Yes, yes. But my perception, after all these years of interviewed and followed, my perception, is that there's simply not knowledge, not the scientific knowledge, has not reached the politicians. Every time that these laws have been voted, like in the Senate, in the U.S., and Ontario, there was not a single scientist that was consulted. It was just done on the basis of, if you look at the Ontario discussion that took, you can go back and hear all the discussion that went. It just be, oh, I like to go to the grocery store when I pick up the,

my kids in the afternoon. So I'd like to have daylight saving. But they don't talk about the morning issue. But so they all, everybody has their own feeling. Oh, I love light. So I'd like to have more light because they think they'll have more light in the winter. They won't. So I think in Canada now, the scientists are going to be consulted.

Yeah, I'm assuming if they consulted you and other scientists that they wouldn't say go to daylight saving time. They would say go to standard time. Oh, yeah. You'll be happier. Okay. So, of course, we still have these. time changes in our lives right now. So let's talk about what we can do to prepare for

these changes in the meantime. So let's start with the one coming up on Sunday. How do we save ourselves from a groggy week? The main advice, well, it's to prepare in each case. In the case of the fall, just use that extra hour. Don't spoil it. Use that extra hour. Generally speaking, always go to bed with darkness. Don't worry. Don't read. Don't have the screen. and just do that, and you keep doing that when the time change come. So here, we have the opportunity, if we are somewhat always a little bit sleep-deprived, to readjust our clock free, without making any effort. So if you go to sleep at midnight, typically, and then you have to wake up at 6.30 or 7,

what you do is you don't say, oh, I have an extra hour now. I'm changing my clock so I can go to bed at this at one o'clock in your current biological clock system. But no, the idea is you keep, you go to bed at the same time so that then you will wake up in the morning, you'll have an extra light so you don't have to use your alarm. Yes, you have a little, yeah, you'll have another, you know, you're going to be able to snoo. And then you keep that. Okay, keep the bedtime you have. Don't change it.

Yeah. But in the spring, the best thing to do is to start going to bed earlier, a week earlier. So it's not, you don't have the one-hour shock. Exercise is very good. Napping is terrific for some people who people like I nap. And as you get older, you have to compensate sometimes for lack of sleep. Naps, not more than 20 minutes, 30 minutes. It's very good, very, very good for the brain, for the heart.

a lot of studies, we've done a lot of studies on that ourselves in our lab. The night's sleep is better than the nap, but the nap in itself, a cup of coffee will help you, will give you vigilance for about half an hour, okay? A nap of 10 to 20 minutes, four hours more of vigilance and functioning. So overall, Joseph, you've convinced me to stick to a bedtime no matter what the clock says. But for those of us who have a hard time getting to sleep, especially at a set time, how can we help ourselves get ready for bed, aside from turning off the lights or putting an eye mask on?

So make sure that you don't exercise late at night, okay? If you exercise, your body temperature goes up and then it prevents you to go to sleep. So that's one trick so that you can lower your temperature. More drop in temperature there is, the better sleep you will have. So there's a host of other things that you can do. You don't eat in the evening because, again, all of this raises your temperature, your digestion, and so on. Should we also turn down the temps in our rooms to help us kind of, you know, trigger sleep? The science suggests that you bring it down somewhat, okay?

so down to 20. Some people say 19 Celsius, 20. But for some people, it doesn't work that much. There are people that have different conditions. But the core issue is temperature and light. Joseph, this has been a really fascinating conversation. Thanks so much for coming on the show. With my pleasure.

That was Professor Joseph DeConink. He's an emeritus professor of Psycho. at the University of Ottawa, where he researches sleep and dreams. That's it for today. I'm Cheryl Sutherland. Our producers are Madeline White, Mikhail Stein, and Ali Graham. David Crosby edits the show. Adrian Chung is our senior producer, and Angela Pichenza is our executive editor. Thanks so much for listening, and I'll talk to you soon.