Commentary
Video
Vulnerable Populations and the Impact of Time Changes on Sleep Disruption
Experts discussed the biological misalignment caused by daylight saving time, emphasizing its negative effects on sleep, particularly in adolescents, and advocating for a shift to standard time to better align with natural circadian rhythms. [WATCH TIME: 6 minutes]
WATCH TIME: 6 minutes
Daylight saving time involves advancing clocks by 1 hour in the spring and returning to standard time in the fall, disrupting the alignment between the sleep-wake cycle and natural light exposure. This shift can negatively impact sleep health by reducing total sleep duration, altering circadian rhythms, and increasing sleep fragmentation. Research indicates that daylight saving time contributes to higher rates of sleep deprivation, particularly in individuals with preexisting sleep disorders, and is associated with increased risks of metabolic, cardiovascular, and cognitive impairments.1 The transition is especially challenging for those with rigid schedules, such as shift workers and students, who may struggle with prolonged circadian misalignment.
In collaboration with the American Academy of Sleep Medicine (AASM), NeurologyLive® held a roundtable discussion where sleep experts shared their clinical perspectives on the health impacts of the time change as well as solutions. The panelists in this conversation included clinical psychologist Jennifer Martin, PhD, who serves as professor of medicine at UCLA and was recently the past president of the AASM, neurologist and sleep medicine specialist Karin Johnson, MD, who serves as the cochair of the Coalition for Permanent Standard Time and the vice president of Save Standard Time, and pulmonologist Seema Khosla, MD, FCCP, FAASM, who practices sleep medicine in Fargo, North Dakota.
In this episode, sleep medicine experts examined the consequences of daylight saving time on circadian rhythms, emphasizing its disruptive effects on sleep patterns, particularly in adolescents. They highlighted how biological clocks remain aligned to natural sunlight cycles despite time changes, leading to chronic sleep deficits when schedules are artificially altered. The conversation underscored the benefits of later school start times in improving adolescent health and well-being, cautioning that permanent daylight savings time would negate these gains. Experts advocated for standard time as a more physiologically appropriate approach, reducing the misalignment between biological needs and societal schedules.
Transcript edited for clarity.
Karin Johnson, MD: I want to go back to Dr. Martin's comment about the farmers, and I think it really brings up the idea of natural time. Our bodies, our animals, our kids, we align to the sun. When you check our cortisol levels and other levels, they stay aligned to the sun even weeks after the time change. So we have this mismatch when we're on daylight savings time between where our bodies want to live and what our school and work, and, you know, our social schedules are telling us to do. Daylight saving time is basically saying, "Get up an hour early and start work an hour early." If we kind of tell most people that, like, "Do you want me to just tell you to go to work an hour early?" they would say, "No, that's crazy!" But that's what we're doing by doing daylight savings time. So we really want to follow that natural time, which is going to give us the best opportunity to have the chance to sleep. We talk about teenagers. They have a natural delay in their rhythms, and they have this drive to be awake until later at night. You can't just say, "Go to bed early." They can't. You squeeze them from the night, making it harder for them to fall asleep at night, and then you're forcing them to get up an hour earlier. It's not surprising that the majority of kids don't get enough sleep. They just biologically can't, especially when we're on daylight savings time. If we go to standard time, where not everyone will get enough sleep, but we actually are giving them a better chance to get close to that.
Seema Khosla, MD, FCCP, FAASM: One of our colleagues really correlated it with the delayed school start time. Like, Dr. Martin lives in California, where they've done a really good job embracing delayed school start times to accommodate the delayed sleep phase of adolescence. But then when we talk about permanent daylight, permanent standard, he said something, and it really crystallized it for me, that in one fell swoop, if we go the wrong way, we eliminate all of the gains that we've made with delayed school start times, and yet that's…
Jennifer Martin, PhD: Yeah, and I actually started calling it—I forgot, but I started calling it appropriate school start times.
Seema Khosla, MD, FCCP, FAASM: That's probably better, right?
Jennifer Martin, PhD: Because, I mean, I think that that is such an important point and again, having just finished raising teenagers before and after the implementation of the appropriate school start times, it made a huge difference. My kids slept more. They were sick less. You know, there was a big impact. And I think that the challenge is, of course, that the adults who work in schools don't have the same phase delay as kids. I think that that's another issue that, you know, we probably all have to deal with, is that we are making some trade-offs with that, but the benefits to kids have been pretty obvious, and it would be reversed.
Karin Johnson, MD: And a lot of people think that if we go to permanent daylight savings time, you know, if we also implement later school start times at the same time then that's fine. We'll fix that problem. The problem is, the current recommendations for later school start times are to start teenagers at 8:30am. If we were to go to permanent daylight savings time, to actually get that same benefit, we would now have to start school start times at 9:30am. You're just chasing your tail, versus, let's get to the time that aligns with the sun and then work our schedules, you know, around that.
Seema Khosla, MD, FCCP, FAASM: Imagine how much additional work that would be, right? It was already hard enough to have consensus at 8:30am, and then when we approach schools about, well, okay, well now it really should be 9:30am, that really eats up, you know, practice time. And then I think we'll get even more pushback.
Jennifer Martin, PhD: There'll be really big challenges then with the misalignment of kids' school day and parents' workday too. If your high schools don't start until 9:30am, parents have to be at work. I mean, it's pretty common for a workday to start at 8am. Now we've got a couple of hours where people need childcare or transportation issues and things like that. So that's a good point.
Karin Johnson, MD: Your exact argument for daylight saving time is to get more time at the end of the day, but later, because you don't get what you're trying to achieve. The main issue is, in summer, the days get longer. We get those longer days. We don't need daylight savings time to give us sun at the end of the day. Summer is going to happen no matter what. But a lot of people connect summer and daylight savings time. That's why we want it. It's great. I like summer. Right now the days are getting longer we're feeling better. It's getting warmer. That will still happen and the days get longer quicker at this time of year. You really don't need that extra daylight savings time to make summer happen.
Jennifer Martin, PhD: And if we need any evidence that that's true, we already have 2 states that do not have daylight savings time, and they are okay. They still have summer, right? And the U.S. territories too, right?
Seema Khosla, MD, FCCP, FAASM: But how we've married those almost and when you speak to people just sort of very casually, their response will be, "We hate the switch. Give us a time that gives us more sunlight," without the recognition that whatever time our clock says doesn't magically change when the sun is out. And yet, it's such a knee-jerk reaction, I think, because of the whole idea of "we're going to take an hour, we're going to save it, and then we're going to get it back at the end of the summer." And I feel like maybe once people take a beat to recognize that, like, like you're saying, Dr. Johnson, that it's that we have connected the longer summer that we look forward to with the seasonal time change, and we do need to disconnect those two.
REFERENCES
1. Sleep experts push for adoption of permanent standard time for public health, safety, and efficiency. News Release. American Academy of Sleep Medicine. Published January 27, 2025. Accessed March 13, 2025. https://aasm.org/sleep-experts-push-for-adoption-of-permanent-standard-time-for-public-health-safety-and-efficiency
