Circadian rhythms influence far more than sleep, affecting neurologic disease expression, treatment response, and overall health. In this episode, Dr. Sabra Abbott discusses common circadian rhythm disorders, the health consequences of circadian misalignment, and practical strategies for managing jet lag, shift work, and disrupted sleep-wake schedules. Learn how circadian biology can shape neurologic outcomes and why considering the timing of behaviors, light exposure, and treatments may improve patient care.
In this episode, Katie Grouse, MD, FAAN, speaks with Sabra M. Abbott, MD, PhD, author of the article "Circadian Neurology" in the Continuum® August 2026 Sleep Neurology issue.
Dr. Grouse is a Continuum® Audio interviewer and a clinical assistant professor at the University of California, San Francisco in San Francisco, California.
Dr. Abbott is an Associate Professor of Neurology at Northwestern University Feinberg School of Medicine in Chicago, Illinois.
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Read the article: Circadian Neurology
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Full episode transcript available here
Dr Grouse: Circadian rhythm disruption affects many of our patients in far-reaching aspects of their general health and has likely personally affected most neurologists at some point in their career. Today, I have the opportunity to interview Dr. Sabra Abbott, who is the author of the latest issue of Continuum on Neurology of Sleep.
Dr Jones: This is Dr. Lyell Jones, Editor-in-Chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about earning CME, subscribing to the journal, and exclusive access to interviews not featured on the podcast.
Dr Grouse: This is Dr. Katie Grouse. Today, I'm interviewing Dr. Sabra Abbott about her article on circadian neurology. This article appears in the August 2026 Continuum issue on Neurology of Sleep. Welcome to the podcast, and please introduce yourself to our audience.
Dr Abbott: Thanks for having me. I'm Dr. Sabra Abbott. I'm an associate professor of neurology at Northwestern, and I'm also director of our circadian medicine clinic.
Dr Grouse: It's really great to have you today. I definitely enjoyed reading your article, and not only did I learn a lot, but I feel like it's really applicable to a lot of topics that come up in clinic when I see patients. Now, I was wondering if you had to choose one key point that readers of your article would take away after reading it, what would it be?
Dr Abbott: I think the most important thing to keep in mind is that time is an important variable in every single thing that we do. And so, it can impact when your patient's disease is at its best and at its worst, and then it also can impact when it's actually most appropriate to provide medications for your patients. There can be times where they may be more impactful and times where they may actually cause more harm for your patients. So, the short answer is think about time always with your patients.
Dr Grouse: On that topic, I was really amazed to learn about the significant health risks associated with circadian misalignment, including even malignancy risks. Can you review some of these risks and why this might be the case?
Dr Abbott: So, I think the risk that we have the most data for is the risk for cancer associated with circadian misalignment, and this comes from a lot of studies that we're looking at patients who are shift workers. The data has actually come back on two separate reviews indicating that shift work could be a probable carcinogen, and we think that that probably comes down to a lot of different factors. So, when you're a shift worker, you are often working in the middle of the night. You may be getting light exposure at a time when you're normally producing melatonin, and that may be one factor that is actually putting you at increased risk for cancer.
Dr Grouse: And certainly, after reading this and hearing all of these things, I'm not surprised that many sleep specialists really dislike daylight savings time, which also is enough of a factor to potentially increase some of these health risks. Do you agree that daylight savings time is something that's contributing to poor health in our population?
Dr Abbott: So, I think it is definitely something that almost all of us want to get rid of, and I think where everybody is in agreement is that we should get rid of these shifts in the spring and the fall. I think the only benefit to those shifts that I see is it does create a time where we start having conversations about your circadian clock, so people become aware of circadian timing twice a year when we have these shifts. Outside of that, that shift back and forth seems to be very problematic. So, we do see both in the fall and the spring an increased risk for car crashes, an increased risk for heart attacks, stroke. People perform worse at work, and so I think in general, we probably should get rid of it. There's a little bit of a debate as to whether we should go to permanent standard time or permanent daylight saving time. I think most sleep and circadian scientists prefer permanent standard time. A lot of people who really like their evening activities prefer permanent daylight saving time, but I think that's also biased by the fact that daylight saving time, everybody has longer days, and I think they want longer days year-round, and you don't get that no matter which way you shift the clock in the winter.
Dr Grouse: That's really interesting. I do see that debate pop up every, I guess twice every year, and I guess there is a silver lining that at least we are all talking about it and thinking about it. I wanted to take a step back about the topic of circadian rhythm disorders in general. Could you just really quickly, like twenty-thousand-foot view, summarize what these main circadian rhythm disorders are?
Dr Abbott: So, at the moment, we primarily think of circadian rhythm disorders in the context of how they impact your sleep-wake timing. And so, at the largest level, we think of them as either intrinsic disorders, so disorders where your internal timing doesn't match up with the environment. The four key disorders there are advanced and delayed sleep wake phase disorders, so you're either earlier or later. You have non-twenty-four, where you actually generally get later and later each day, so it's like you're living on Mars. And then we have irregular, where you have multiple bouts of sleep that happen both night and day. And then the other two are the extrinsic disorders, so these are shift work disorders. So, you may have a normal functioning clock, but the external environment is forcing you to do things you wouldn't normally, or jet lag, where you again have a normal functioning clock, but then you end up having to shift multiple time zones faster than you can adapt to. Now, I think the interesting thing, and we can talk about this more if you want, is that we are moving into thinking of circadian rhythm disorders as being much more than just abnormalities of sleep-wake timing, and I think that's kind of where the future of the field goes.
Dr Grouse: Tell me more about that.
Dr Abbott: So, I think as the article gets into beyond just these kind of classically recognized disorders, we realize that circadian disruption can play a role in almost any other medical disorder that you can experience. And so, we can see circadian disruption as either a symptom or a potential cause of many other disorders. And then also in the optimal care of pretty much any patient, thinking about all of these other factors that they're experiencing on a day-to-day basis, whether it's their light exposure, whether it's the timing of their meals, whether it's the timing of their medications, all of those can play a role in their overall health and improving your ability to care for them.
Dr Grouse: Now, I did find it really fascinating. This was not something that I had really been aware of prior to reading your article about the fact that it really can make a difference about when you time particular medications for particular types of neurologic conditions just related to the circadian rhythm. And really interesting was the epilepsy connection. Can you tell me about how that affects how we should be dosing anti-seizure medication?
Dr Abbott: So, I think the epilepsy connection is an interesting one that definitely needs far more studies. So, at this point, a lot of this data is really coming from observational studies, looking at when patients have received medications and then how good their outcomes are. And in epilepsy, I think a lot of us tend to time anti-seizure medications so that patients get more of them in the evening and lower doses during the daytime. And I think a lot of this has been driven a little bit more by the fact that many of these medications are sedating, so we tend to put the more sedating medications at bedtime. But it turns out that outcomes in patients are actually better if they get higher doses at night and lower doses in the morning. Now, this is sort of theorizing at this point, but it could either be targets of these medications or your ability to uptake these medications across the blood-brain barrier may change with the time of day component. So, at this point, these are still really observational studies, but I think an area where we really need to do a lot more work.
Dr Grouse: Well, I look forward to hearing more about other ways that we'll learn how best to manage our medications for circadian rhythm function. Now, I wanted to ask, which circadian rhythm disorder do you think is the hardest to treat, and why would that be the case?
Dr Abbott: So, I'm gonna give you two answers to that. In terms of the primary circadian disorders that I see come through my clinic door, I would say cited non-24. These are patients who have normal vision, but they act as though they are living in a world without these external light time cues. And so, they, every single day, get a little bit later and a little bit later, and it's really, really hard to get them from a 25-hour schedule back onto a 24-hour schedule. The second part of my answer to that is shift work disorder, and those, I would say, are much more common patients to encounter. I think every single one of us, as we've gone through our medical training, has probably had some degree of shift work disorder, difficulty sleeping when we need to, staying awake during our shifts. But it's still really hard to figure out what we should be doing because, one, it's a multi-component system, so anything that I do to change your shift schedule has trickle-down effects to every one of your coworkers, and so we can't just tell one person, "Change what you're doing." It's also really hard to figure out what we should be doing. Should you only be working nights forever and ever and become purely nocturnal, and should we adapt everything to that, or we-- should we find some sort of compromise so that you can work the night shift but still have time to socialize and spend time with your family during the daytime? And how do we do all of that while still optimizing your health? And so, I think from a patient population, that is really a large problem we don't have a good answer to yet.
Dr Grouse: Sounds like it's something that you really have to customize to every single patient who walks in and their, their particular scenarios.
Dr Abbott: Absolutely.
Dr Grouse: Jet lag disorders is another circadian rhythm disorder that I think we all have had some personal experience with. Any tips or tricks on how to manage jet lag going east or west, or any resources that you recommend that can help us manage this, or we can advise to our patients?
Dr Abbott: Yeah. When we're talking about individualized, personalized treatment, I would say jet lag absolutely is way up there at the top of the list because it's not only a matter of where do you currently go to sleep and wake up in your current time zone, it is how many time zones are you going across to get to where you're going? Do you wanna keep the same schedule when you're at the new time zone? And all of these other factors in terms of how long you're gonna be there. When are you gonna come back? Does it make sense to fully adapt yourself to that new schedule? With that in mind, the general tips are if you are heading east, generally your goal is to shift everything earlier, and if you're heading west, generally the goal is to shift everything later. There are a lot of online calculators you can use where you can put in your current time zone, your destination time zone, and it will give you very specific information about when you should be getting light, when you should be avoiding light When melatonin may be helpful as another time cue that can help shift you. But again, it really depends on which direction and how many time zones and what time you're gonna arrive. I would say the practical tip that I have is whatever you do when you get to the new time zone, um, most of the time international travel involves overnight flights, so you may arrive in the morning. Resist the temptation to take a nap as soon as you arrive because that's just gonna make things harder and harder to adapt to. So, get out, be active, eat on the new time zone, try to push through that day, and then the homeostatic drive for sleep is gonna help you through that first night.
Dr Grouse: Great tip, and definitely a tip I have failed to follow in past trips and regretted greatly afterwards. There were some other really great points that you made that as an ambulatory neurologist I hadn't thought of that was really, really helpful, including when we take care of patients in the hospital, of course, we-- we're always careful about, you know, potential sort of things we can do to minimize delirium. But in fact, there's probably a lot of things we can do to minimize disruption to circadian rhythms, which we already know that if we're not careful about, can be deleterious to health. What are some things that you recommend generally for patients who are admitted regarding monitoring and treatment that we can try to do to mitigate that effect?
Dr Abbott: So, I would say the number one most important thing that you can do, and I did this every single day when I was on the wards, is when you walk into the patient's room for rounds in the morning, turn on the lights, open the curtains. We did an interesting study a few years ago because there was all of this discussion of nighttime disruption to hospital patients and a lot of concern that they were getting too much light and too much interruption to their sleep at night. But what we found out was actually the bigger problem may be that none of our patients are getting light during the daytime, and so they've just lost that amplitude of light rhythm. And so as much as you can maximize daytime and opening those curtains, turning on the lights, giving them a bunch of light during the day. And then obviously, on the opposite end, you wanna make sure that they're getting dark at nighttime. Being really thoughtful about what your patients actually need to have done while they're in the hospital. And so, do they really need to have vitals every four hours in the middle of the night? Is that gonna change their outcome, or are they just sitting there waiting for insurance to approve their rehab bed, and they're probably gonna be fine overnight without that disruption? I think those are the easy things that you can do. The slightly harder piece is there's a lot of debate about whether we really need to be doing four AM labs on all of our patients, for example. Obviously, that's disrupting everybody's sleep. It's making a phlebotomist be a shift worker. It's problematic in many respects, but at the same time, you need to collect the labs so the labs can actually be processed and you can have the results, and they can be available for rounds, and so you can discuss them so that then you can discharge the patient on time. And so, it's a whole set of moving parts that are sometimes a little hard to optimize specifically for the patient.
Dr Grouse: Certainly, worth a discussion to have, though, and all really great tips. Another question kind of on that same vein. A lot of patients ask for something to help sleep at night. Melatonin is something we often give as sort of an easy, relatively gentle treatment that can help with sleep. Do you agree that that's a good idea? Is that something that you would generally recommend?
Dr Abbott: So, I would say that melatonin on the overall risk versus benefit spectrum probably has very low side effects for your hospitalized patient. At the same time, we actually fought this battle here. On many of the hospital formularies, you have very high doses of melatonin, so it's five, ten milligrams. Now, the problem with that is it takes you long enough to metabolize that ten milligrams of melatonin that it is still gonna be in your system the next day. So, then you go to round on the patient the next day and they're groggy and they're out of it, and it may not be that they've neurologically deteriorated, it may still be that they have melatonin still in their system. So, if you are going to use that as sort of a first-line low-harm option, I would stick to one to three milligrams.
Dr Grouse: Great. One to three milligrams is something I've often heard. Is that generally optimal dose and timing for melatonin, uh, you suggest for patients, or how do you approach thinking about the dose and timing?
Dr Abbott: So, this is where it gets a little more complicated because we actually don't recommend using melatonin as a general hypnotic. It's not that great for treating insomnia in general. So, where we do more often use melatonin in circadian patients is as a phase-shifting stimuli. So, this is something that if you give melatonin at a specific time, it can either move your clock earlier or move your clock later. And that tends to be something that is a little more challenging to sort out. It's a conversation to figure out where your patient currently is from a rhythm standpoint, where you're trying to move them to. So not something I would use typically for insomnia, but more if you're trying to adjust somebody's timing.
Dr Grouse: Excellent point and great recommendations. Now, switching gears a little bit, you had mentioned and you alluded earlier that circadian rhythm disruption can be something that we find in certain neurologic diseases and conditions we all treat and may even be an early sign of some of them. What are some general conditions in neurology that we see circadian rhythm disruption?
Dr Abbott: So, I think one of the areas where it's often an early sign of a disorder is in neurodegenerative disorders. So, we often do see that that typical daily rhythm and amplitude, and what I mean by that is that sort of difference between how active you are during the daytime and how inactive you are at night. That tends to become dampened and more fragmented even before you start to see some of the other signs and symptoms of neurodegenerative disorders, so things like Alzheimer's. So, it often can be kind of an early hallmark that something else might be coming. Now, other ways that we can see circadian rhythm disruption in other neurologic disorders, I think probably the more under-recognized is in any disorder where a patient may have decreased mobility, sort of overall inactivity during the day. Maybe they have chronic pain, maybe they have really bad migraines, so they're spending lots of time in a dark room disrupting their sleep schedule. All of these things can lead to patients having more of an irregular pattern, so having chunks of sleep and wake that are just sort of distributed randomly throughout the night and the day, and they lose that overall rhythmicity to their behaviors, which then translates into a loss of rhythm and light exposure, a loss of rhythm in food intake. All of these things can kind of build on each other.
Dr Grouse: Well, that's a really good point. You know, often we think of, you know, sleep disruption causing a lot of these problems, like migraine being a very common one. But don't think about as much of the fact that the migraine itself could be contributing to the sleep dysfunction. So, a very, very interesting point there. Now, I was curious, having read the article, what isn't in the article that you wanted to put in?
Dr Abbott: So, I think the focus of this article really was primarily on the neurologic aspect of things, but I do think it's important that if people are interested in this and excited about this area, that they recognize that it's not just neurologic disorders that are impacted by this. There's a lot of really exciting research going on in the area of oncology, for example. There's some really cool research showing that the timing of your first dose of chemotherapy actually dramatically impacts your outcomes. And so, I think there are a lot of really interesting areas where thinking about your circadian system can really optimize treatment, not just within the area of neurology.
Dr Grouse: That's amazing. Well, I'll be really interested to see where that heads. And then of course, on that same topic, any new treatments or diagnostic modalities on the horizon that our listeners should be on the lookout for?
Dr Abbott: So, I think as a field, we are always looking for better ways of looking at circadian markers within the clinic. And so, multiple groups, including our own, have been looking at blood tests. So, is there a way that with one or two samples we can actually get a profile of what your current biological time is? And so, I think those blood tests are still being validated in patients with disorders. We've mostly looked at them in healthy controls. I think other areas we're looking at new diagnostic tools to actually get a sense of how people are responding to their environment. So, we're doing a study looking at using pupillometry, which is a way of measuring how your pupil responds to light, and using that to figure out whether you may or may not be somebody who responds well to light or poorly to light, and can we tailor your treatments for that? So, I think we're looking at many different ways that we can improve diagnostics in the outpatient setting.
Dr Grouse: Well, that's really fascinating. I can't wait to hear more about what may be coming around the corner. Thanks so much for sharing, and I'm sure you've inspired some of our trainees considering a career in sleep medicine. Thank you so much for sharing, and I really again encourage all of our listeners to check out her wonderful article.
Dr Abbott: Thanks for having me. It was great to have a chance to talk about this, and I second your hope that more trainees will be interested in sleep and circadian medicine. It's really an exciting field to get into.
Dr Grouse: Again, today I've been interviewing Dr. Sabra Abbott about her article on circadian neurology. This article appears in the August twenty twenty-six Continuum issue on Neurology of Sleep. Be sure to check out Continuum Audio episodes from this and other issues, and thank you to our listeners for joining today.
Dr Monteith: This is Dr. Teshamae Monteith, associate editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at continpub.com/audiocme. Thank you for listening to Continuum Audio.