S1 E15: Light & Your Circadian Rhythm


Amanda: Hey, this is Amanda, women’s health dietitian.
Emily: And I’m Emily, nutritional therapy practitioner.
Amanda: And this is the Are You Menstrual? podcast where we help you navigate the confusing world of women’s hormones and teach you how to have healthy periods.
Emily: Each week we will be diving into a different topic on women’s health and sharing our perspective using nutrition, female physiology, and metabolic health.
Amanda: Our goal is to help you wade through conflicting health information and empower you on your healing journey.
Emily: We hope you enjoy it.

Emily: Hey, ladies, so in this episode, we are going to be covering another foundational topic for hormone health. And that is light exposure and circadian rhythm. I’m sure you’ve heard of both of these buzz phrases in the wellness world, as they’re both very important. And you can’t really talk about one without talking about the other because they go hand in hand. And many women don’t realize that they both have a significant impact on hormone health. So as you probably already know, our bodies take in everything in our environment as information, and light is a really big part of that. So the focus most often in the wellness sphere is reducing blue light exposure, which is going to be your, your screen light and your artificial light. But we are going to talk about also how increasing sunlight is just as crucial. So even, it might even be more critical to be honest with you than reducing blue light. But we’ll get more into that. Our light exposure impacts our circadian rhythm. And this is our body’s internal clock, which Amanda is going to cover in much more detail in this episode. So our circadian rhythm is what trickles down to impact digestion, hormones, sleep, energy, and so much more. So we hope you enjoy this episode, because once again, we have a lot of good info for you.

Amanda: So what is circadian rhythm? It really comes down to the fact that it’s our body’s natural internal process that regulates our sleep-wake cycle, and it repeats about every 24 hours, it’s actually slightly less than 24 hours I learned. And I was like, oh, everyone always just says 24 hours, so repeats almost pretty much every 24 hours. And it’s most impacted by the light and dark cycles that are in our environment. So that’s why, you know, Emily mentioned that everything in our environment is information. Because that, our body takes in that outside information, whether it’s like light, stress, heat, you know, temperature, that sort of thing. If you’re somewhere where maybe you have like a pretty chaotic environment that you’re living in, then all that, all those things are going to be processed by the body, and it’s going to impact how things are functioning. And sometimes if it’s really positive, and you have lots of great light exposure and a good environment that helps you balance your hormones and heal and makes your body more resilient. When you have a more stressful environment, maybe you don’t get outside a lot, maybe you’re indoors, don’t have a lot of that good sunlight exposure, then that can obviously have more of a negative impact on that internal clock.

And so why does this circadian rhythm matter for our hormone health? The big thing is that not only does our circadian rhythm regulate our hormone production, but it also regulates our digestion, metabolism, and energy production. So these are all things that we’ve discussed that have, they trickle down, and they’re going to impact our hormone health. And when we think about it, that circadian rhythm, that internal clock, is actually programmed into us. If you put someone in a room without them knowing what time it is, their body will naturally adjust to that circadian rhythm. They’re going to produce melatonin in the evening and get sleepy at night. In the morning they’re going to have their stress hormones that make them feel more awake. And then that peak production is going to occur in the afternoon. So when this cycle gets disturbed, for example, if we go to bed at like four in the morning, then we’re going to feel awful the next day. And I think that’s when we can kind of all relate to if you’ve ever had jetlag, or if you stayed up super late, you’re, maybe you’re traveling, that you just feel terrible, almost like you’re hungover that next day. And if you continue to abuse this circadian rhythm for months on end or years for many people, it’s going to put ourselves at risk of hormone imbalances, digestive issues, and increase that stress response within the body.

Emily: I think it’s so fascinating that the body just innately knows, like you said it has that internal programming. And it just goes to show how intelligent it is but also how connected to our environment we are which I think is just very interesting. But let’s talk a little bit about how your circadian rhythm impacts the body. I’m going to talk about during the daytime So one big way is digestion. And it’s going to help regulate our stomach acid and our digestive enzyme production. So we’ve talked about in the past why this is so important for breaking down nutrients, digesting the food you eat. That’s pretty much the basis for everything else in the body, right? We need these important nutrients to help every system work. It’s also going to increase the hormones and enzymes for absorption as well. It increases beneficial bacteria for digestion also.

So as you can see, the circadian rhythm plays a huge role in just how we digest and absorb our food. But it also impacts blood sugar. So did you know that too little or too much blue light can actually impact insulin signaling? And that’s a huge factor for blood sugar balance. So we need insulin to shuttle the blood sugar into our cells. And without proper insulin signaling, this is going to go all haywire. So light exposure means a lot when we think about blood sugar. And we’ll kind of go into this further in the episode as well. And then lastly, our metabolism—we need to make energy during the day. And that’s going to be affected by our circadian rhythm as well. So it’s going to help energize us in the daylight hours. And as Amanda will talk about, kind of slow us down during the darker evening hours.

Amanda: So it’s really, it’s making it so that everything is getting going during the day. And then at nighttime, as a big part of that circadian rhythm is your cortisol dropping. And as that stress hormone decreases, our body’s able to make more melatonin. And that’s a hormone that actually helps us feel sleepy, fall asleep easily, and then stay asleep throughout the night and wake up feeling like you’ve had restful sleep. So it’s really important for sleep quality. We also do a lot of detoxification at nighttime. It’s really important to get that consistent sleep and hopefully avoid waking up too much at night, mainly for that liver detoxification. But we also work on our brain’s natural detox process which is called the glymphatic system—all that happens at nighttime.

So if you are someone that’s struggling with brain fog, cognitive issues, and you aren’t sleeping well, this is a huge reason why. And then, of course, things like recovery. I mean, I feel like a lot of people know this, especially if you exercise, strength train, anything like that. If you’ve ever been an athlete, you know that sleep is one of those things…it’s pretty much drilled into your brain of like you have to get good sleep, otherwise, you’re not going to recover properly, your muscle tissues aren’t going to rebuild. But that can go for anything—illnesses as well, surgery, anything where your body is trying to repair and recover—all that stuff is happening at nighttime. And then lastly, we do have a shift in our gut bacteria again at night. So Emily mentioned during the day, we have that shift, and we have more bacteria that actually help us break down and digest and absorb food at nighttime. It shifts to bacteria that support detoxification since that’s going to be that main process that’s occurring at night.

Emily: So as you can kind of guess our circadian rhythm impacts so many different systems in the body. And these are all going to directly and indirectly impact hormone production and just overall balance, right? So super important. And we’re gonna go into what influences our circadian rhythm the most. So what kind of things during the day or during the night are we doing or not doing that’s going to impact this internal clock. And I think two of the biggest ones are going to be eating and light exposure. So eating regularly and being mindful of your light exposure can help support circadian rhythm balance and reduce stress and compensation within the body, which is super important for keeping a healthy circadian rhythm.

Amanda: If we’re eating all of our food or a good chunk of it late at night, that is going to be a little stressful to your body. And it’s also gonna throw off that circadian rhythm. Right? If your, your body’s getting that signal of like, okay, I’m taking all this energy I have to do all this digestion now…it’s, it typically doesn’t go well. And Emily and I were just talking about this before we hit record. And she was saying how if, you know, she eats a lot of big snacks later at night and she’s up later than her body is used to then she feels like she doesn’t digest it as well. And it makes sense, because say, like, you’re up past your typical bedtime, your body isn’t used to that. Your body temperature has most likely already dropped, which slows down your metabolism, helps you sleep well, stay asleep, keep the blood sugar balanced. And so it would make sense that you wouldn’t do super great with digesting things at nighttime. So avoiding all the food later in the day is huge. We see that a lot and I don’t think that women really know… one, we need to eat during the day. We got to fuel all the things that we’re doing brain, physical activity, all that stuff, but then, too, when we have all that food at night it really does throw off that circadian rhythm.

Emily: Yeah, and it can be kind of a double-edged sword, because I’m a huge fan of the bed time snack which I know Amanda as well, but I’m also someone who needs to be in bed by no later than 9pm. So when I’m eating a snack at 9pm, my body doesn’t always do as well, like you said Amanda, it’s probably because my temp has already dropped, my body is preparing itself for sleep. And so it’s just eating throughout the day for me is huge to make sure that I don’t necessarily need this big bedtime snack right before I’m hitting the hay. So that’s a big one. But this is going to be, I feel like resonant for all of you, or maybe just me, but exposure to blue light and screen time, as I mentioned earlier, that’s going to be really important to reduce as we get closer to bedtime. And we’ll go into the specifics on this. But I’m sure most of you by now have heard how blue light does affect sleep. And it has to do with your cortisol and your melatonin production. But this is just going to be huge as far as just kind of turning off the screens, getting your phone out of your hand, wearing your blue light blocking glasses to help really wind down and to increase that melatonin in the blood.

Amanda: Yeah. And if you, if you’re someone that has blue light in your bedroom, that’s another big one. So it’s, it’s kind of flip flopping your body’s schedule, right? We’re not following, we should be following what’s happening outside. So when, when it starts to get dark, you want to start to dim the lights in your environment. And that’s going to help avoid that cortisol production, like Emily mentioned. And that’s going to make it so that you can make melatonin. Cortisol and melatonin are antagonists. So if your cortisol is high, your melatonin is going to be low. And that’s why things that we can do to regulate our food throughout the day consistently, light exposure…they have such a big impact. So if you’re someone that has a TV in your bedroom and keeps that on while sleeping, that can impact your melatonin and sleep quality. Or maybe you have bright lights that can get in there, like, trying to get some sort of shades, blackout shades, those can also help block some of that. And that’s going to help support how much melatonin you’re making, how deep and restful your sleep is.

Emily: Another one is skipping meals or having an erratic eating schedule. I joke that our bodies are very much like toddlers. And if you have a toddler, you’ll totally get this. They love routines, and they love to be in the know. And when you kind of push them out of their routine or do something new or different, they freak out. I feel like our bodies are very similar to this. The routine of having a regular eating schedule makes them feel safe, it makes them produce energy, and we want to be doing that during the day at very predictable times to support our circadian rhythm.

Amanda: And then another one is like if you have a lot of changes in your sleep schedule, probably the most classic case that I see is having a pretty similar sleep schedule on the days that you work or which is usually weekdays for most people. And then on the weekends or on your days off it’s like drastically different. You know, maybe you’re staying up a few hours later waking up a few hours later, that will impact your circadian rhythm and that internal clock as well. And this typically shows up in how well you sleep. So like do you fall asleep easily, do you stay asleep that night? Are you getting into that deep sleep and the quality of your sleep so having lots of changes in that sleep schedule? Obviously traveling and experiencing jetlag is kind of the example I used in the beginning for what happens when that circadian rhythm is off. So imagine if you’re doing this on a weekly basis to your body—it’s, it’s a lot. Doesn’t mean you have to wake up at the exact same times but trying to get within like an hour is going to be a lot less stressful for your body than going for like a three to four-hour gap difference.

Emily: Lastly, minerals play a huge part in your circadian rhythm, because a lack of minerals can negatively impact sleep and adrenal health. So when you have a depletion in minerals, that’s often a sign of an exhausted stage of stress, where our stress hormone patterns are dysregulated, and this can definitely make sleep difficult. So we want to make sure that we’re getting enough minerals, we’re balancing them out in order to support our sleep patterns. And then just not being in a flight, fight or flight state all the time, we don’t want to be in that sympathetic state 24/7 because that can definitely throw off our sleep as well.

Amanda: So if you’re someone that’s done a hair mineral test and you’re wanting to see if your mineral status could possibly be impacting you, you’d want to look at your metabolic type—we have a whole episode on this. And if you’re that fast metabolic type, it’s pretty common to have sleep issues. But the fast 4 is the most common, because these are the people that are in that lower mineral state, a lot of the minerals are below the optimal line, things are depleted. So your thyroid and your adrenals have slowed down but your nervous system is still stressed, basically the most amount of dysfunction that you can have show up on your hair test. And when that nervous system is out of balance with the rest of your body, that internal clock is going to be off. So if you want, if you’re like, I don’t know if my minerals show that I could have sleep issues, it’s usually the fast metabolic type and the fast 4.

So what happens to our bodies when this circadian rhythm is off, like, say you into the category of, or some of the categories that we just mentioned. Like maybe you’re getting lots of blue light at nighttime, maybe you don’t have a consistent sleep schedule, maybe you don’t have a consistent meal schedule, you don’t eat breakfast, you eat a lot of your food later in the day. What happens—and this is a explanation that I love from Dr. Mariana Figueiro, where she said—if you don’t get the timing signals your body needs, you will most likely fall asleep and wake up around 15 minutes later every day. Pretty soon your body’s clock will be out of sync with your daily schedule. So it doesn’t always happen overnight. And I think this kind of perfectly describes our health journey, especially from the moment that you kind of realize that all these issues and symptoms are popping up for you. It’s usually like we reach a point where like, this is the day that everything kind of changed. And it’s all that time leading up to that day that your body is slowly compensating and getting more and more out of balance. And so I feel like if you have that idea in your head of like, okay, we’re slowly getting even less than an hour of dysregulation out of balance, every single day, it can creep up on you, like all of a sudden, you’re just completely off.

Emily: Correct, and the more wrong signals that we give our body at the wrong times, this will shift your clock even further out of balance. So it can just kind of compound on itself further and further until you feel like you’re experiencing jetlag all the time, as Amanda mentioned. So you’re just tired all the time, you just can’t get the right amount of sleep or good quality sleep, you’re eating at the wrong times, your digestion is off… And then of course, the cascade of hormonal chaos, right, it’s really important to get your biological clock in sync with the environment in order to support all of these natural systems that are taking place in our body.

Amanda: And it’s the, when you think about it, like, having jet lag all the time. That like really resonates. And I think it will resonate with a lot of people listening to this podcast, because one of the most common main complaints that women come to see me with is fatigue, you know, fatigue, no appetite, poor digestion, constipation, difficulty falling asleep, staying asleep—that’s literally jetlag, right. Just like pure exhaustion and all your systems are off. And I think that the world that we live in today, like, this is just what we kind of get, you know, we’re always in a rush. People are not prioritizing eating at regular times, you know, we’re pushing off, we’re working through lunch or not eating it at all. We’re intermittent fasting and skipping breakfast. We’re always on the go. And we’re inside a lot, at least most people. So the people that are most at risk for having this imbalance in their circadian rhythm and not having that internal clock match their external clock, which is basically the light and dark cycles outside, those are people that are constantly looking at a screen, usually spend a lot of time inside, the older population for sure. Right? If you, I used to work in nursing homes, and I think about like we, they did not get outside enough, you know. They’re not getting all that good blue light exposure from the sun. So our biological clock is going to be completely thrown off.

And I think about, like, what are the different ways that we can measure this. Obviously, with your energy, you could look at cortisol levels. So if you ever do like a Dutch hormone test, and you look at your cortisol pattern throughout the day, that’s obviously one way to measure it. Melatonin production at nighttime, but even your body temperature, right? Like, we obviously, we’ve talked about basal body temperature I feel like so much on this podcast, and we went pretty in depth on that PCOS part one episode. And when we think about your, your temperature is the lowest the first thing in the morning when you wake up, and then it rises throughout the day and it goes down again at nighttime. So you could measure your body temperature throughout the day and see if you’re experiencing those shifts, and if it starts to go down at nighttime, and that’s going to give you some indication of how that internal clock is doing. So lots of different ways to kind of look at this stuff.

But I think if we’re going to dig deeper into one specific area that we’ve, we’ve talked about before in circadian rhythm it’s really our meal timing—that’s something we have a lot of control over—everyone has to eat. So when we think about how our bodies are actually more sensitive to insulin and carbohydrates when it’s light outside, a lot of people that talk about weight loss or have specific weight loss programs really do harp and focus on this. And they talk about eating when it’s light. And I don’t always agree not eating when it’s dark, because I think that sometimes you might need a bedtime snack or something like that—I don’t think it’s bad. But I think really trying to prioritize eating within an hour of waking and then trying to eat consistently throughout the day and not waiting until nighttime can do wonders for your internal clock.

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Emily: Now, we love to harp on eating breakfast within an hour because this is going to signal to your body, hey, you know, I’m done sleeping, I’m done fasting, let’s kickstart that metabolism. It just keeps you in sync with that circadian rhythm when it’s light out and you are up at ‘em, you’re trying to produce energy, eating is going to be the best way to signal to your body, aside from getting light in your eyes, which is another great way. But definitely eating that first meal is just going to be really helpful for kickstarting all the different processes and getting your metabolism going for the day. And of course, we want to make sure that you’re eating a balance of protein, fat, and carbs. So just trying to make sure you keep your blood sugar stable and pairing those macronutrients together for that.

Amanda: And then trying to eat somewhat similarly day to day. I like how Emily said how like toddlers, kids, they have a schedule, right? When we’re younger, we all follow a schedule, we have a bedtime routine, all these things that we implement. And we do it because we know that it’s healthy for kids, but it’s healthy for adults, too. And so if you can tell your body and give it that consistency of like, okay, we eat within an hour of waking and then we eat at these pretty similar intervals throughout the day, at least most days a week, I would say—it doesn’t have to be perfect every day. This is not about perfection. It’s just about getting your body into a schedule, giving yourself a routine. And it does help you eat more as well. I think when we don’t have that planned out, like things just get busy, and it’s really easy to be like, oh, I didn’t even, I didn’t have my lunch. I didn’t even think about when I was gonna eat today. It’s not in my schedule. Now it’s something that you’re skipping or you’re eating at like four o’clock, you know. So I think trying to be somewhat consistent. If you’re eating really erratic meals right now, I would just say start with focusing on one. Our clients always start with breakfast if they don’t eat breakfast pretty soon after waking that’s the first thing we recommend focusing on. And once it’s probably the easiest, like, it’s, it can be hard for some people, but once they get it down, like they’ll, they’ll have that habit for the rest of their life.

Emily: Again, if you’re someone who doesn’t wake up craving food, start with something small like gummies. We tell our clients start with a gummy or two, you know, that has some, some protein, some fat, carbs, but it’s just a great…

Amanda:  Eat three gummies. One gummy? 

Emily: Listen, my gummies are really big. I don’t know about you, but… 

Amanda: Oh, are they? Mine are like the, I use the silicone ice cube tray so mine probably aren’t as big.

Emily: Yeah, mine come in like, they’re like a cup and I cut them in half. So it’s a pretty big gummy, use your own, use your own discretion, like you can decide how much gummy you want to eat. But that’s just a really quick way to get in your breakfast first thing in the morning and get that metabolism revved. And then I would say just put a timer or an alarm on your phone. If you really need a reminder to eat lunch during the day, set one on your phone for noon, or whenever you want to eat and make sure that you don’t just ignore it. Like that’s a really great way to just kind of get yourself more into the habit of eating regularly. And actually taking a break from whatever you’re doing to eat. I had to do that when I worked a full-time job and editing and magazine publishing. Like it was so busy that if I didn’t put a timer on my phone and an alarm to you know, tell me to eat sometimes I would just go the whole day without stopping. I would maybe have like a protein bar at like three, which is just insanely unhealthy. So that’s a good tip for all of you busy, busy people out there.

But the last one we want to mention for meal timing is just to try to avoid eating all of your food at nighttime. And this is not a tip to kind of say that eating at night, like Amanda said, is bad or will make you gain weight or, you know, anything like that. It’s not, it’s not necessarily going to make or break your health. It’s just a matter of teaching your body to expend energy throughout the day and not preserve energy throughout the day. Because when we do that we’re going to, it’s going to lead to stress hormone imbalances, right, and that’s going to make falling asleep more difficult. So just trying to kind of, I don’t even want to say front load your meals, but just eating regularly. That’s kind of the whole point of this, of this tip and not so much at one specific time of the day, especially at night right before you’re about to go to bed.

Amanda: And everyone needs to eat all day. I think this is something that’s really easy to think oh, I have PCOS, should I do intermittent fasting? Or if you have insulin resistance, you’re trying to put more time between your meals. Negative. I think that everyone, I’m sassy because I’m in my luteal phase, it’s fine. I think everyone has to eat regularly. It’s just probably one of the most common questions that I get when we, especially when if we do like a newsletter on this topic, or an Instagram post, people are like, oh, but I have x, y, and z so I should only eat like two or three times a day. And it’s, and like everyone’s different. If you found something that really works for you, obviously stick with it. But we find for the majority of people, like it doesn’t matter if you exercise a ton or not, it doesn’t matter if you have a sedentary job, you have to fuel your body. Or even if you have weight loss goals it literally doesn’t matter. Because if you’re undereating, then your, everything’s gonna slow down… metabolism slows down, then you have all these hormone issues crop up. And that’s really where insulin resistance will start to kick in. Make sure that you are fueling your body throughout the day.

And I know it can feel weird, we can have a lot of feelings come up around food. Snacking can be really hard because you’re kind of like, I have a few clients that they they’re like, I feel like I have a lot of weight to lose and, like, I don’t need to be eating so consistently. And it’s like every, everybody deserves nourishment. We have to remember that no matter what you want to change about it—avoid waiting until nighttime eat all that food. Even if you just think about your bacteria, like how Emily was going through the daytime stuff, you know you, we make more bacteria that helps you digest your food and you make more stomach acid during the day. So if you don’t take advantage of that, of course you’re going to have GI issues and sleep problems at night. But that, those are kind of like the meal timing tips. Just start slow, implement those like one at a time. And then eventually I think you, your appetite improves, and that part of your internal biological clock does start to match that external light and dark cycle.

When it comes to the other big one, which is light exposure, this is the one that most people focus on. But food and meal timing is just as important. But the light piece is that other part of information that we’re getting from the environment. And when we are exposed to light, we produce neurons. And those are just messengers that share information in the body. These are activated by bright light and they’re deactivated at nighttime when, or when we don’t have that light exposure. So this is why when we look at a bright screen at nighttime, it’s harder to go to sleep because your body thinks that it’s daytime and I should be making cortisol and my digestion should be going. When we spend a lot of our days indoors, and we’re not getting that light exposure, you can have the opposite and be very tired and fatigued during the day and then even feel that way when you wake up in the morning.

Emily: And this is something that our ancestors definitely benefitted from without all the technology, because if you think about it, you know, before electricity before screens and electronic devices that emitted these lights, they didn’t have a choice, right? They rose with the sun and they went to bed when the sun went to bed. So there was really no other choice, and their circadian rhythms were very much intact, as you know, generations of people and as a society. Whereas in the world we live in today, unfortunately, this is very disorganized. We are living in a disorganized cycle of difficulty sleeping, lots of fatigue during the day, and this is all being driven by our light exposure and our meal timing or lack thereof. So it’s just really one vicious cycle. And of course, we have to be grateful for, you know, the te

Amanda Montalvo

Amanda Montalvo is a women's health dietitian who helps women find the root cause of hormone imbalances and regain healthy menstrual cycles.

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