Sleep, Light, and Circadian Rhythms

Brent: Why is the prescription not just wake up and stare at my phone?

Helen: I mean, that's a good point. You will get more blue light, but you're probably not maximizing your light. But I would agree, screens—if there's one time to look at screens and get a whole bunch of blue light from screens, morning is fine.

Brent: A rare pro screen.

Helen: I'm not saying it's great for your mental health, but from a circadian point of view.

Brent: Welcome to the Life Lab by Death Clock. I'm your host, Brent Franson. The mission of Death Clock is to help 100 million people live ten years longer. Today, we speak with Doctor Helen Burgess about circadian rhythms. Doctor Burgess is a professor in the Department of Psychiatry and a co-director of the Sleep and Circadian Research Laboratory at the University of Michigan.

Brent: We talk about blue light blocking glasses. We talk about these lights that you use when you wake up. There's even glasses that you can use when you wake up. We talk about melatonin. This is really a conversation about sleep hygiene and the role that circadian rhythms play, and how you can adjust your circadian rhythm. We spend a fair amount of time talking about how you can move your circadian rhythm back.

Brent: If you want to go to bed a little bit earlier and wake up a little bit earlier. She's very deep on this topic. She spent her career studying it. She's a wonderful guest. I hope you enjoy.

Brent: Doctor Helen Burgess, welcome to the show.

Helen: Thank you. Thanks for having me.

Brent: So today we're going to talk, I think, primarily about circadian rhythms. I love this topic because I'm somebody who has historically not been a great sleeper. I've been focusing much more on my sleep, and my sleep's been improving, so I'm excited about that.

Helen: Oh, nice.

Brent: But before we get into it, give us a sense of your day job and your background.

Helen: Yes. So I'm originally from Australia, hence the accent. I did my PhD on sleep and circadian rhythms many years ago. I started my career studying sleep and circadian mechanisms in healthy individuals, and then in the last ten years or so, I've moved on to studying sleep and circadian rhythms in different disorders. We look at a wide variety of disorders.

Helen: We have a study on fibromyalgia, for example, a widespread chronic pain condition, a study on HIV, PTSD, and inflammatory bowel disorder. A wide variety of illnesses. It's really because sleep and circadian rhythms apply to everything. But that's what we do. I'm in the psychiatry department at the University of Michigan as a professor, and I also co-direct the Sleep and Circadian Research Lab.

Brent: Let's just start with the basics for the average person who's not suffering from bipolar, fibromyalgia, or depression. But I want to get to that. First, what is a circadian rhythm in the average person? What do we need to know about it?

Helen: Circadian rhythm—the word "circadian" is Latin for approximately a day, so it's around a 24-hour rhythm. It's pretty much seen in everything that you could study in the human body. Classic rhythms, for example, would be the core body temperature rhythm, which is elevated during the day, decreases at nighttime, hits its lowest level during your sleep episode, and then comes back up.

Helen: Hormones, temperature, and our behavior as well. Of course, from a circadian point of view, we would even think of sleep as a circadian rhythm behavior that changes across 24 hours.

Brent: Okay. So when we think of the circadian rhythm, I think we think, "Oh, I get some sunlight in my eyes, and that's what tells me it's day, and then based on that I get sleepy at a certain time." What I hear you saying is, yeah, that is a circadian rhythm, but we have many circadian rhythms.

Brent: Do we think about them differently, or would we say all of these different rhythms around core body temperature, etc., are set by this master circadian rhythm that is sunlight in the eyes in the morning?

Helen: Yes. You're right. We do have this central clock in the hypothalamus in the brain that will actually run on autopilot. It has its own internal clock that is genetically determined, but also influenced by behavior. The timing of that internal clock can indeed be shifted by light exposure, but it's not driven by light exposure.

Helen: It has its own internal mechanism; it's just a little clock ticking away. For example, there are classic studies where you bring people into a lab and have them in dim light for many days. The clock will still run on 24 hours. It might run at a different time because there's no light exposure, but it will.

Helen: It will still run. More recently, we know that in addition to that central clock, pretty much every cell in the body has its own little internal clock running. The current thinking in the field is those cells come together at the level of the organ—we call these peripheral clocks.

Helen: So there are some in the liver, kidney, gastrointestinal system, and heart. They seem to provide localized timing control within the level of the organ, but they are definitely still receiving that central signal from the master clock. Often in the field, we talk about the model as the conductor of the orchestra: the conductor is the central clock, but there are all these little peripheral clocks doing their own thing as well.

Brent: Is this true across species? Do ants have a circadian rhythm, and elephants have a circadian rhythm, and just anything moving around the planet has a circadian rhythm?

Helen: Pretty much, yes. There are different ways to study it, but in terms of changes in behavior across 24 hours, yes, there is. If you think about it, it makes sense because we evolved on this planet with a 24-hour light-dark cycle. Part of the reason why I think we have this circadian system is it improves our adaptation to the environment.

Helen: Actually, there's some speculation that we probably developed a circadian rhythm before we even developed vision because you need to be out at the right time to find your food, and you also don't want to be out at the wrong time because you might get eaten. So there are arguments out there that the circadian system is so fundamental to our survival that some argue it's more important than vision, for example.

Brent: So evolutionarily, it's very ancient and might predate vision.

Helen: Yes, exactly.

Brent: Okay. So there's a genetic component and a behavioral component. I assume there's a huge behavioral component, but the most obvious one would be when do I expose my eyeballs to sunlight or something that mimics sunlight. And then there's a genetic component, which would be the classic: some people are night owls, and some people are early birds.

Brent: That's going to determine how that circadian rhythm gets set. How do you think about the genetic component?

Helen: Yeah. If your parents were night owls, you're probably going to be a night owl. There's a little bit of an aging effect; we tend to become a little bit earlier as we age, with a peak in lateness or night-owlness around our 20s in adolescence and young adulthood, which we experience. But yeah, definitely individual differences.

Helen: There is a significant genetic component to that, but it can also be exacerbated in some cases by our behaviors, or in other cases mitigated against by other behaviors. So we really need to think about what we're doing. If we stay up late, we are getting a lot of light exposure, either from indoor lights, screens, or our phone, for example—a lot of blue wavelengths, which mimic that sunlight that pushes us later and makes everything worse.

Helen: If we're a little bit more conscious about what we're doing and try to minimize that evening light, get more morning light, and maybe try to wake up a smidge earlier, that's going to shift our clock earlier and put us in a better position.

Brent: But the genetic component still really matters. A teenager who's forced to get up every day for class at 7:30 exposes themselves to morning light earlier than they naturally would, yet they complain day after day and don't necessarily adjust. So the genetic component can basically overpower the daily conditioning of putting sunlight in the eyes.

Helen: It can. I think the case of adolescents is a little bit different because part of the reason for this big biological push for them to be later relates to puberty. They get hit with this hormonal signal that actually pushes them later. We see that in non-human models as well in other mammals—this influence of puberty.

Helen: The other thing going on with adolescents is the behavioral component: homework, after-school activities, and next thing you know, they're very sleep-deprived, which makes waking up in the morning even more difficult. In some of the research that we've done, we know that if you're chronically sleep-deprived, you actually become less responsive to light.

Helen: So morning light is probably having less of an effect on them as well. Adolescents are an extreme example. In the field, sometimes we call that the perfect storm because there are so many different components coming in that they really are a worst-case scenario, apart from shift work.

Helen: And of course, they're out there driving too; they just got their licenses, which is a scary thought. They are a little bit unique. But to get back to your point, genetics definitely play a role. If you're really an extreme night owl, it can be difficult to try and shift back.

Helen: You're correct that some people who are extreme night owls fit the criteria for a disorder called delayed sleep-wake phase disorder, where they're going to bed somewhere between 2 and 6 a.m., really struggling to get up in the morning just to keep a job. They can shift themselves earlier with their sleep timing and morning light exposure.

Helen: As soon as they stop doing that, it's pretty easy for them to drift later again. So it is a daily routine that we're looking at to help people with.

Brent: How malleable is it if I'm a night owl? Let's say I tend to go to bed at 11 and get up at seven, and I really want to shift to going to bed at nine and getting up at five. How malleable is it?

Helen: Well, 11 to 7 we wouldn't really think of you as a night owl. We would think of you as right in the normal range.

Brent: I'm giving myself away as an early bird. Yeah.

Helen: Yeah, exactly. I think 11 to 7 or even 12 to 8, we're thinking, "Oh, that's not too late."

Brent: I think the question is, if I want to move it two hours up, if I want to get up earlier consistently and change my circadian rhythm—whether I go from 6 a.m. to 4 a.m., or 10 a.m. to 8 a.m.—how malleable is it?

Helen: It's pretty malleable. If your natural tendency is sleeping 11 to 7 and waking up around seven, we can shift you earlier. We usually don't recommend what is called a "slam shift." You can do that, but it's painful and doesn't feel good. Instead, we suggest people start nudging themselves earlier, and everyone can try it out to see what works for them.

Helen: If you really are a night owl, shifting early is definitely harder to do, but usually I would recommend shifting sleep about half an hour earlier each day. Some people prefer 15 minutes, along with morning light. Something that can also help with shifting earlier is low doses of melatonin, which we can get into.

Helen: Light and melatonin have an additive response: they come together to help shift the clock earlier. But as you said, once you hit that 9-to-5 sleep schedule, you'd really need to be careful about trying to keep to that schedule, because when we sleep obviously regulates when we get light.

Helen: So you would have to work pretty hard to stick with that. Of course, what usually happens is life kicks in, things happen, you drift back to 11 to 7, and then once that's dealt with, you're like, "Okay, I'm back on the path now to shifting myself earlier."

Brent: Okay. So the recommendation would be to shift it slowly: go half an hour earlier for a week, and then another half hour, doing it over the course of a month or something.

Helen: Actually, I meant about half an hour a day.

Brent: Oh, so just do it over the course of four days, as opposed to one day? If I wanted to go two hours earlier, go to bed 30 minutes earlier four days in a row? That's pretty quick, actually.

Helen: Yep. A tricky factor that comes in here is our circadian clock keeps track of its own time, working out whether it's the biological day or the biological night. The reason why we don't like people to do these sudden, massive shifts—apart from the fact that it doesn't feel great—is that two to three hours before you normally wake up at night is an important time for the circadian clock.

Helen: That's where it makes the shift from the end of the biological night to the start of the biological morning. We usually don't like people waking up more than an hour earlier than normal at most. If you wake up earlier than that, you might be enthusiastic and think, "I want to wake up three hours earlier this morning and get all my light."

Helen: There is a risk that light could be interpreted by your circadian clock as late-night light and actually push you later, which you want to avoid. The circadian system is a little slow to shift, so slow and steady really wins the race.

Brent: The other thing I believe to be true related to this—which is annoying—is that you want to get up every day at the same time, seven days a week. Sleeping in on the weekends, particularly if you're trying to adjust your circadian rhythm, is just not the way to manage sleep. How do you think about wake-up time and consistency of wake-up time?

Helen: You're right, it really is important. That's a new focus in the sleep field right now: thinking about the regularity of sleep timing. You want a consistent wake time, which is going to be easier to do if you're getting enough sleep. The American Academy of Sleep Medicine recommends anywhere between 7 to 9 hours a night.

Helen: You will have a sense of your own need. Some people feel great on seven; others really need nine. Bedtime is also important because it needs to be early enough that you'll get good sleep. In our studies, we don't just focus on wake time.

Helen: We also think about what your latest bedtime should be to make sure you get the sleep you need. I always say to people that we don't want to be the fun police on the weekend. It's probably the same with dietitians—what do you want to tell people?

Helen: That they can never, ever eat cake? No, you just want to tell them to do it in moderation every now and then. So if you want to sleep in just for the enjoyment of it, I think it's great. I usually recommend no more than half an hour if possible. But if you've been following a regular routine, you really should be waking up pretty naturally around the same time.

Helen: The only factor that would cause you to sleep later is if you're sleep-deprived. Once you're really well adjusted, a lot of the time you should even be waking up before your alarm.

Brent: It seems particularly important in the context of shifting sleep earlier. Is it similar to cognitive behavioral therapy for insomnia, where you have a fixed wake-up time and go to bed late, and when fixing insomnia you're really tired but can't sleep beyond that wake-up time without messing up the program?

Brent: Is that true? If I'm shifting my sleep earlier, is it similar in that sleeping in every once in a while is fine in a normal course, but if you're in the process of transitioning to an earlier sleep time, you should really avoid it?

Helen: Yes, for sure, because we're trying to optimize the shifting of the circadian clock, which is best done with a clear signal: regulated light exposure. The clearer the light signal we provide, the more efficiently the clock will shift. If you start messing around with wake time, that obviously influences when you first get light exposure.

Helen: Next thing you know, the clock is getting a slightly different message each day about when the day is beginning, and it shifts back and forth in response. So give it a nice, clear, consistent signal, and you'll get a much better response.

Brent: Okay. What about the opposite end: let's say I'm on day two, I've moved my sleep time up an hour, and I'd probably be more likely to have trouble falling asleep than waking up earlier. Should I just stay in bed until I fall asleep?

Brent: It just is what it is.

Helen: Yes. You brought up insomnia, and over time, a driver of insomnia can be people lying in bed unable to sleep, starting to associate their bed with a place of stress. First of all, expect it to take longer to fall asleep.

Helen: This is where something like melatonin could be helpful for sleep onset. Yes, it's going to be harder to wake up in the morning because your clock is shifting and you're forcing yourself to wake up early. Give yourself another three days or so to allow your clock to settle into that rhythm.

Helen: After that, you should start feeling pretty good. You can tell when you've reached that point: you're not sleep-deprived and you start waking up before that earlier alarm clock.

Brent: Okay. The key is to make it easiest to want to sleep, make sure you don't sleep in, and avoid ruminating or creating a bad relationship with your bed over falling asleep. Let's talk about melatonin. As I understand it, with most melatonin supplements, we're taking way too much. It's not regulated, but it has a role. The research is strong in jet lag. What do we know and not know about the quality of melatonin supplements, and how is it best used in this context?

Brent: We're taking way too much. It's not regulated but it does have some role. The research is strong in jet lag. So what do we know and not know about I don't know the quality of melatonin supplements. And then how is it best used in this context.

Helen: Melatonin is definitely tricky, and I like to think of it as having three different uses. Your intended use will influence the dose you take and the timing. The most typical use—and the one most people have experience with—is melatonin as a sleep aid.

Helen: It's not really strong enough to be a hypnotic, but as a sleep aid, it's usually taken in a dose range of 3 to 5 mg about half an hour before you want to fall asleep. There's very good evidence that it will help you fall asleep faster, though mixed evidence on how much it reduces night awakenings.

Helen: For some people it really helps, and for others it doesn't, but it certainly helps people fall asleep faster. The second category—where the newest research is coming out—is the anti-inflammatory effects of melatonin. In literature, people usually take a dose of at least 6 to 10 mg to start seeing a reduction in inflammatory markers.

Helen: Most of that has been seen in people with pre-existing heightened inflammation. I don't think we know whether reasonably healthy people will see reductions in inflammation. The third category is using melatonin to help shift the clock.

Brent: Just as measured by high-sensitivity CRP, that kind of measurement? Yes.

Helen: That kind of thing, yeah—all the different cytokines, for example. Systemic inflammation and inflammatory markers. The third bucket, which is least familiar, is using melatonin to shift the clock. The research shows that if you want to shift the clock earlier, the time to take melatonin is about five hours before your usual bedtime.

Helen: If you go to bed at 11 p.m., we're talking around 6 p.m. The recommendation is to take a low dose, around 0.5 mg, because at 6 p.m. you don't want to experience the sleepiness side effects of melatonin.

Helen: Half a milligram at that time is best according to studies. There shouldn't be endogenous melatonin in your system then, so it tricks the clock because melatonin binds to the central pacemaker in the hypothalamus, serving as a feedback signal.

Helen: It will actually shift in response to that. We also know that melatonin and light can be used together to get even larger phase shifts.

Brent: So in your third use case, if I take it five hours before bedtime, it's out of my system by the time I go to sleep, but it signals to my body that it's time to sleep. The body starts the process of going to sleep a little earlier, easing the transition to an earlier bedtime.

Brent: And that eases the transition to an earlier bedtime.

Helen: Yes. If you take low-dose melatonin at 6 p.m. and try to fall asleep at 11 p.m. but aren't tired enough, you could take a higher dose then just for the sleep onset effect. Some people in the field argue that this double-duty approach can be useful.

Helen: I've found that taking the low dose is enough for me to fall asleep at the earlier bedtime, but people can experiment to find what works best for them.

Brent: Should we be concerned about melatonin supplements interfering with our body's natural ability to produce melatonin? We produce it naturally, and adding supplements can interfere with natural production in other medications, causing dependency.

Brent: How do you think about that?

Helen: That's a great question. Many substances feed back and influence their own production, but that does not appear to be the case with melatonin. Our endogenous levels tend to decline as we age, but taking supplemental or exogenous melatonin on top of that is fine.

Helen: It will be fully washed out within about 24 hours. Regarding purity and accuracy of dosage, you should go with larger, reputable companies that send formulations for independent testing, indicated by stamps like USP on the bottle.

Helen: This is true for all supplements. Buying the cheapest generic version over the counter is not always the best idea. Choosing a reputable company that pays for independent testing is the way to go.

Helen: Going with a reputable, large company that can pay for independent testing is the way to go.

Brent: To make it simpler, what brand do you use in studies?

Helen: We use Natrol. I should disclose that I am on their scientific advisory board, but Natrol is what we use in our studies.

Brent: So the word "nature" with an "ol" at the end?

Helen: It's Natrol.

Brent: Natrol. And we can get that on Amazon?

Helen: You can get it on Amazon, Costco, CVS—it's one of the major brands, maybe even the top one.

Brent: Is it true that over-the-counter melatonin supplements contain way too much melatonin compared to what you would recommend? Should people be concerned about dosage options?

Helen: Yes, consumer demand has driven larger doses, which is concerning. Taking very high doses can override your existing circadian rhythm by keeping high levels in circulation all day, which confuses the clock.

Helen: There is interest in higher doses for potential anti-inflammatory benefits, but that is still being explored.

Brent: You mentioned being on their scientific advisory board. How should we think about perceived conflicts of interest? The strong argument for pharma/supplement connections is that you want researchers tightly linked to industry so products reflect current science.

Brent: The cynic would say Big Pharma pays for favorable research findings. How do you explain these relationships to people, balancing research with formal corporate ties?

Brent: And so how do you think, like how do you talk to people about how we should think about that in our head, that you are doing research and you're, you know, you're you're pushing the envelope in terms of what we know about the role of, of melatonin, but you also have a formal relationship with a I don't know, a for profit company.

Brent: I see these relationships as largely positive, though not exclusively. It helps people understand why it's beneficial and where to be cautious.

Helen: Conflict of interest was a major issue historically with NIH funding, especially in psychiatry from the early 90s to early 2000s. I am fully funded by the NIH for my research.

Helen: We handle it much better now. For any study where we administer melatonin, an independent group creates a conflict-of-interest plan. Part of that plan ensures I don't see the final study results until the end.

Helen: I am not in a position to shape results. Any relationship must be reported to the conflict board, reviewed, and directly related to my research to help answer our scientific questions.

Helen: A board reviews everything. Consulting is limited to about four days a year. I am required to accurately report all activities.

Helen: Under the Sunshine Act, drug and supplement companies must report these payments too, so there is oversight on both ends. Third-party review ensures everything remains reasonable.

Helen: I should never be in a position to publish papers claiming benefits that don't exist.

Brent: I'm actually supportive of this. With lightly regulated supplements, we want companies to have advisers like you guiding dosage and formulations.

Helen: Four days a year, yes.

Brent: Four days a year is very light! You sit down quarterly, answer questions, and share what current research shows about user consumption.

Brent: Right.

Helen: We educate them on science while they share consumer demand, trying to find a middle road where scientific products appeal to users.

Helen: There is a drive toward high doses of melatonin, and many adolescents use it regularly. While certain groups benefit—like children with autism spectrum disorders—typically developing adolescents should only use it short-term.

Helen: Kids with neurodevelopmental disorders or autism spectrum disorders are greatly helped by nightly melatonin according to literature, but typically developing adolescents should only use it short-term.

Helen: Short-term use during Daylight Saving Time shifts, back-to-school transitions, or jet lag is fine, but nightly use in adolescents raises valid concerns.

Brent: This dynamic exists across healthcare when patients demand unrecommended treatments or scans. Extra-strength over-the-counter options sell better, pushing higher dosages regardless of science.

Brent: Well, okay, doc, you give it to me or I'll go find a doctor who does. It does seem to be that dynamic is very tricky. And in the case of these medications, it sounds true for melatonin. Is there even such thing as not extra strength, etc.? And, you know, it's clear that the extra strength over-the-counter painkillers sell better.

Brent: Higher milligram products sell better, so having scientists push back is crucial. Back to circadian rhythms: melatonin low-dosed 5 hours before bed helps shift rhythms earlier, while taken 30 minutes before bed helps sleep onset.

Brent: Don't do that. Here's what's here's what's actually good. And I don't try to figure out the tension between the science and consumer demand. But so back to circadian rhythms. Thank you for the thank you for the detour. So melatonin we can use it five hours before bed in low dosage. If we're trying to adjust our circadian rhythm earlier, if we use it 30 minutes before bed it's going to help us fall asleep.

Brent: It's unclear if it helps middle-of-the-night awakenings. We aim to wake up at the same time daily. How should we approach morning light exposure upon waking?

Brent: When I get up at my normal wake time, what should I ideally do?

Helen: Ideally, get a lot of light—sunlight is best. Work it into your routine, like walking the dog outside first thing in the morning.

Helen: If it's winter or too cold, sitting by a large window receiving direct sunlight is a great alternative inside your home.

Helen: There are light boxes and wearable light glasses. Circadian science shows light pulses up to four hours continue having an effect, but we recommend one hour daily as a practical, effective duration for shifting the clock.

Helen: Wearable devices automatically shut off after an hour while you check email or do chores around the house.

Helen: Then it turns itself off, and you're done for the morning.

Brent: How do clouds affect light exposure?

Helen: Clouds reduce light intensity, but going outside on a cloudy day still provides significantly more light than staying indoors.

Brent: In months where it's completely dark outside when waking up, going outside yields no circadian benefit. What should we look for in a light box?

Helen: Yes.

Brent: What lux measurement should I look for in a light box?

Helen: Classic light boxes claim 10,000 lux, but by the time light reaches your eyes from a distance, you receive closer to 3,000 lux.

Helen: Light boxes work well if positioned nearby while doing morning emails or watching TV. In studies, we used two light boxes on either side of a TV screen.

Helen: We eventually moved to wearable devices. Consider brightness and wavelength: circadian photoreceptors in the eyes are most sensitive to 480 nanometers (blue-green light).

Helen: Devices like Re-Timer emit blue-green light around 500 nanometers, matching photoreceptor sensitivity as effectively as large white light boxes.

Brent: That's the brand name.

Helen: Re-Timer is the brand name. They emit blue-green light near maximum photoreceptor sensitivity, making them as effective as large light boxes.

Helen: Okay.

Brent: So I buy those glasses and wear them for the first hour of the morning?

Helen: Yes, use full intensity for an hour. Keep room lights on so the blue-green LEDs don't feel too glaring in a dark room.

Helen: Turning on room lights improves the light therapy and visibility without glare.

Brent: Are they uncomfortable to wear?

Helen: They sit below your field of view so you can see straight ahead. Looking in a mirror, you'll see a green ring lit up around your eyes.

Helen: Adjust the nose piece until you see a green circle around each eye, and you're good to go.

Brent: Regarding blue-light blocking glasses and phone screens at night: why isn't the morning prescription to just wake up and stare at your phone?

Helen: You get blue light from phones, but it doesn't maximize light exposure like sunlight or dedicated devices. Phone light suppresses melatonin slightly, but morning screen time is fine for circadian needs.

Helen: It suppresses melatonin, but morning screen exposure is completely fine from a circadian standpoint.

Brent: A rare pro-screen argument!

Helen: Not for mental health, but circadiandly it's fine. Personally, I avoid looking at my phone during the first hour of the morning to exercise and reset.

Helen: So I have that break.

Brent: Inexpensive tools like melatonin, light glasses, and blue-blockers seem effective. Do blue-light blocking glasses in the evening help shift sleep schedules?

Brent: Is that true? How should we think about blue light in the evening, and what do you think about blue-light blocking glasses?

Helen: Blue-blockers cut out potent wavelengths. Two to three hours before bedtime, the clock prepares for the biological night by signaling the pineal gland to secrete melatonin.

Helen: Dim light 2-3 hours before bed allows melatonin secretion to signal nighttime across the body.

Helen: Bright modern home lighting and screens disrupt this process by flooding environments with light.

Helen: Blue-blockers, dimming lights after sunset, screen filters, or Night Shift mode on iPhones help reduce evening light exposure.

Helen: Night Shift makes iPhone screens warmer after sunset. If you use screens heavily at night, blue-blockers are a good investment.

Helen: Wearing blue-blockers a few hours before bed as part of a daily routine helps people shift their sleep schedule earlier.

Brent: What about red light? Some people replace house lights with red bulbs after sunset. Is red light effective or recommended?

Brent: Or would you recommend something like that?

Helen: Circadian photoreceptors are least responsive to red light, making red nightlights ideal because they minimize nighttime circadian disruption.

Helen: A fully red environment isn't strictly necessary, but the scientific rationale behind using red light at night is sound.

Brent: I take a morning sauna with customizable lights. I've used red light, but should I switch to bright white or blue light in the morning instead?

Brent: Red light in a morning sauna might not be best for starting my circadian rhythm.

Helen: Use bright white or blue light in the morning, and reserve red light for evening saunas.

Brent: How do circadian rhythms interact with conditions like depression, fibromyalgia, or bipolar disorder? Does depression disrupt circadian rhythms, or does circadian disruption exacerbate depression?

Brent: Are both true? What is the link here?

Helen: In bipolar disorder, people with bipolar I or II have heightened photoreceptor light sensitivity, which can sometimes trigger mania.

Helen: In fibromyalgia, chronic pain often leads people to stay in dark, indoor environments, inducing winter-like depression due to lack of light and routine.

Helen: Staying in dark homes without routine worsens symptoms. We implement a plan with a regular sleep schedule and one hour of morning light daily for four weeks.

Helen: Symptoms worsen due to natural behavioral responses like staying in the dark. We establish regular sleep schedules and daily morning light exposure.

Helen: Morning light for one hour daily over four weeks leads to remarkable reductions in pain and acts as an effective antidepressant without pharmaceutical side effects.

Helen: Studies show remarkable pain reduction. Morning light is as effective as pharmaceutical antidepressants without side effects.

Brent: And research centers around healthy circadian maintenance for symptom reduction?

Helen: In inflammatory bowel disease, intestinal clock gene expression shows cellular-level disruption even between flare-ups, proving intrinsic circadian involvement.

Helen: Circadian interventions help treat intrinsic disease disruption alongside symptom reduction.

Helen: We use circadian interventions to target intrinsic cellular disruption and improve disease outcomes.

Brent: Looking 20 years into the future, what advancements in circadian research excite you most?

Helen: Measuring individual circadian clock timing accurately remains challenging. Current methods measure endogenous melatonin onset in dim light over six hours.

Patients sit in dim light taking saliva samples every half hour to pinpoint when melatonin rises at the start of the biological night.

Helen: And melatonin is suppressed by light. So it's a pretty involved process. We have to, sort of six hours or so before you normally go to bed. We have to bring you into a dim environment. Although we do have kits now where people can do this in their home. And we have an app developed that kind of guides people through it, but it is involved as burdensome.

Helen: We need better human circadian timing measures. Researchers are analyzing blood metabolite profiles across 24 hours to estimate melatonin onset from single blood samples.

Helen: Using machine learning on blood metabolites or wearable heart-rate data could track real-time circadian timing, enabling personalized daily advice apps.

Helen: Machine learning algorithms mapping blood metabolites or wearable data could predict melatonin onset and provide real-time circadian guidance.

Helen: Wearables and algorithms will eventually provide accessible, accurate real-time circadian tracking and dynamic health advice.

Helen: Inexpensive, real-time tracking will push the field forward by tailoring circadian interventions dynamically.

Helen: Tracking longevity, aging, and inflammation is another crucial frontier. Shift work disruption increases inflammation, but light treatment effects on inflammation remain understudied.

Helen: We need more research on how light treatment and sleep schedule shifts reduce systemic inflammation beyond sleep and mood benefits.

Helen: Broadening research to explore non-sleep benefits of light therapy will help unlock further health outcomes.

Helen: We have work to do, but the future is promising.

Brent: Thank you for your incredible work and for taking the time to speak with us today.

Helen: Great meeting you, and thank you.

Brent: The Life Lab by Death Clock is recorded in Boulder, Colorado, and San Francisco, California. Produced by Patrick Gudino, music by Patrick Lee, and hosted by Brent Franson, founder and CEO of Death Clock.