Shift Work And A Bold Claim

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Shift work can be brutal, but it doesn't have to be. Welcome to a healthy shift. My name is Roger Sutherland, certified nutritionist, veteran law enforcement officer, and 24-7 shift worker for almost four decades. Through this podcast, I aim to educate shift workers using evidence-based methods to not only survive the rigors of shift work, but thrive. My goal is to empower shift workers to improve their health and well-being so they have more energy to do the things they love. Enjoy today's show. And welcome back to another episode of a Healthy Shift Podcast. You are most welcome, and I want to say thank you so much for tuning in to another episode of this podcast. Now, today, I'm going to make a big statement to start off with here. Blue light does not inhibit your ability to go to sleep. There you are. I said it. You hear everything around blue light and its impact on sleep. But I'm going to come out and say that blue light does not inhibit your ability to go to sleep. Now let's go through this whole podcast and then I will give you the answer to that at the very end and why I said it. Now I've got your attention. Let's go through the function of the eye and the suprachismatic nucleus and how all of this ties in in relation to light for our circadian rhythm. I've covered this topic a number of times.

Quick Favour Rating And Review

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Let's go into it in a little bit more detail in a way that I hope that you will be able to understand. But before I go on today, I want to ask you. Lot of people are listening to this podcast at the moment. A hell of a lot. And all you've got to do is open the app, turn it on, and away you go and you listen to it. But I have to research it, script it, talk about it, record it, put it up there, and then you get it. That's a lot of work. And you get it for nothing. Can you do me a favor? Can you literally just give it a review? Can you go on Spotify, go back to the main page, and after you've listened to it, just actually give it like five stars? And on Apple, you can see where you can review it. Go to the main page and where the stars are, hit the review. And if you be or the the um yeah, the rating, so you can rate it. And then if you could be so kind to put a review at the bottom, I've got to tell you, it really does help significantly with this show. It helps it to get out there, it helps people to uh more people to find it, more people to get some evidence-based information, and more people to get shocked with the fact that blue light does not inhibit your ability to fall asleep. I know, controversial, right? And you're gonna think, what would he know? He doesn't know. How could scientists be wrong?

Two Light Systems In Eyes

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Science actually supports this. So let's get to the end of it and then I'll detail it and explain to you why. First of all, most people think that your eyes exist for only one reason, and that is to see. But this is only part of the story because your eyes run two completely separate systems. Now, one of those systems is created for vision, the other one controls your biology. And the second one may be the most important for your long-term health. Now, today I want to explain how light entering your eyes actually sets your body clock, controls your hormones, and it also signals to the body when it's time to start repairing itself. And once you understand this, the way that you think about light will change, should change, must change. All right, so let's go through that. Let's go through to start off with the two different light systems in your eyes. Now, inside the retina, there are cells which are called rods and cones. Now, these are the cells that allow you to actually see the world. They detect contrast, they detect color, shapes, and movement. And what they do is they build an image that your brain interprets as sight, movement, what you can see, what you're actually looking at right now. But around 20 years ago, scientists confirmed that the retina actually contains another type of light sensor. Now, these cells are called intrinsically photosensitive retinal ganglion cells. It's a mouthful, isn't it? So let's just shorten it to IPRGC cells. Now, these cells do something very different. They do not create images, they do not help you to recognize a face, they do not help you read. Their job is very simple. What they do is they just detect environmental light, a particular type of light, which I'll get into, and then they report that directly into the brain's timekeeping system. So you have one visual system that helps you see the world, and the other system that tells your brain where it is at in time and space,

The Brain Master Clock Explained

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as in what time of the day it is. So let's talk about the brain's master clock to start off with. Because when these IPRGC cells detect light, a particular color of light, they send signals through a pathway that ends up in a tiny region of the brain, which is called the supracosmatic nucleus. Now, this structure sits in the hypothalamus and it contains roughly 20,000 neurons. But it is tiny, and despite being tiny, it actually runs the body's entire circadian timing system. So it is your body's master clock, and it is minute, it is smaller than the tip of a pencil, it controls your sleep cycles, it can controls hormone release, your body temperature, it controls your metabolism, your immune activity, and all of these are following daily rhythms which are directed by this particular central clock. And that clock needs one key piece of information every day. It sits in the brain, it sits within the skull, it cannot see. It's got one avenue of light, and that comes from the IPRGC

Morning Light And Melanopsin

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cells in the eye. Not the vision, it comes from that particular cell in the eye. So why does morning light matter so much? Because when morning light enters your eye, the IPRG cell C cell activates. Now, these cells contain a light-sensitive pigment, which is called melanopsin. Now, melanopsin is especially sensitive, highly sensitive to blue-riched wavelengths that are common in daylight. And guess what color it is? You wouldn't believe it, it's the color of blue sky. That is the color, 480 nanometers. So these cells, these IPRGC cells, are actually very super sensitive to blue. But they're also sensitive to cyan and green, but not as sensitive because they also signal daylight as well. So when the daylight actually hits these cells through your eyes, they send a signal to the brain that it is daytime. The brain then begins aligning the body's internal rhythms with the external day. So once that light hits the eye, goes to the brain, it tells the brain, oh, daytime, suppress all the night hormones, bring up, fire up all the day hormones, let's get going. What does it do? Cortisol begins rising. Your alertness actually increases, your body temperature starts to gradually climb. And your metabolism shifts into a daytime mode where it performs optimally. Now, this is how your brain synchronizes your internal clock with a rising sun, with daylight. And without that signal, the system literally just drifts and drifts and goes further and further out of line because it's only guessing from there on in. Now, when this system drifts, your sleep, your mood,

Melatonin Signals Nightly Repair

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your energy, and your metabolic health all begin to really suffer. So this hormone that signals darkness, because it's one of the most important signals that's controlled by this light pathway, and that is the hormone melatonin. Now, melatonin is produced mainly in the pineal gland, but the timing of its release is controlled by the brain's master clock. Now, during the day, this light entering these IPRGC cells signals to the supracasmatic nucleus and tells the pineal gland, suppress melatonin, it's daytime. And this is exactly what should happen. Now, melatonin is not meant to be high during daylight hours. In fact, it should be non-existent. But once darkness arrives, once the sun goes down and that IPRGC no longer sees blue, cyan, or green, the light levels drop, then this signal actually reverses. And what it does is it signals to the pineal gland, it's dark. We need melatonin. So melatonin starts to get produced and it begins to rise. Now, these levels usually start increasing a few hours before sleep time. So not long after darkness and a few hours before sleepness. Now that rise in melatonin is called dim light melatonin onset, or abbreviated to Dilmo in research literature. Now, this rising signal tells the body that nighttime has begun. Now, what is important also, and I mean extremely important for you to understand, this is where the blue light exposure severely impacts on your health. Many people think of melatonin as a hormone that helps you to fall asleep. But that is a far too simplistic way of actually looking at it. Melatonin is literally just a hormone signaler to the body that darkness has been registered. But melatonin signals that darkness to the rest of the body. And when melatonin rises in the bloodstream, it starts to tell every organ and system in the body that night has arrived and your body temperature drops and your metabolic rate slows, and the repair processes in your brain, in your body start to increase, and your immune activity changes as well. And cells begin switching from daytime activity into nighttime maintenance. This nightly repair cycle is

Melatonin As An Antioxidant

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a major reason consistent sleep timing is just so important. Now we also know that melatonin has another extremely important role, and that is that it acts as a powerful antioxidant. And we are learning this through science now because research is showing that melatonin can actually neutralize reactive oxygen species and reactive nitrogen species inside cells. What are you talking about, Rog? Well, these molecules are often called free radicals. And free radicals are produced during normal metabolism. But if they start to accumulate, what they do is they damage DNA, proteins, and also cell membranes. And melatonin literally helps to limit that damage. It can also stimulate the activity of other antioxidant enzymes such as superoxide dysmatuse and also glutathione peroxidase. Because of these effects, melatonin is often described as a cellular protector during the biological night. Now, melatonin and abnormal cell growth, let's talk about this because this is important, particularly for you shift workers, because there is evidence now that melatonin has what researchers call oncostatic properties. Now that means that it may slow or inhibit abnormal cell growth. You know what I'm talking about here, don't you? Laboratory and epidemiological studies suggest that melatonin can actually influence pathways that are related to tumor growth, DMA repair, and also immune surveillance. For example, melatonin can influence cell cycle regulation and apoptosis in certain experimental models. Now, it can also affect how cancer cells respond to oxidative stress. That does not mean that melatonin alone prevents cancer. Let's put that on the table and get quite clear. But it does show that the nightly melatonin signal appears to play a role in maintaining cellular stability. Now, this is one reason why circadian disruption has become a major area of research in cancer biology.

Cancer Risk And Circadian Disruption

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And this is another reason why shift workers are diagnosed with cancers, particularly breast and prostate cancers, at a much higher rate than anybody else's. Circadian disruption of modern light. The challenge today is that humans now control light in ways that biology just never evolved for. For most human history, light exposure has followed a simple pattern. Bright sunlight during the day, darkness after sunset. That's the end of it. But today, more than 85% of our time is spent indoors under artificial light. Then at night, we expose ourselves to bright artificial light. Those screens, LED lighting in our roofs, our mobile phones, our tablets, that TV. All of these produce light, blue light, that hits our eye and activates those IPRGC cells. And when those cells detect light at night, they are sending the same signal to the brain. Hello, it's daytime. And when that happens, melatonin is suppressed, your body clock shifts to later, sleep timing drifts, and the normal repair signals of the night become a lot weaker. Now, why does this matter for shift workers? Because the issue becomes even more significant for the people who work shifts.

Modern Light Breaks Our Biology

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Night shift workers are exposed to bright artificial light during a biological night. Remember that body clock is still functioning on that normal diurnal rhythm. At the same time, they're often trying to sleep during daylight hours. And that pattern sends mixed signals to your circadian rhythm. Now the brain receives light cues that conflict with the body's internal timing. And this is called social jet lag. What your eye sees and what is actually occurring in time is wrong. For argument's sake, you're working night shift and you're out and you're driving around, but you're seeing light. Where your body internally is thinking, wait a minute, we should be sleeping now. Your eye is seeing blue light and it's telling it, no, no, no, no, it's daytime. It's daytime. So it suppresses melatonin and it keeps you awake. This is the problem. Now that pattern sends entirely mixed signals to our circadian rhythm and creates chaos within our biological system. This is where we get our brain fog, fatigue, we get gut issues from, we get um mental health issues, we get all sorts of problems from this. Over

Why Shift Workers Suffer More

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time, this can lead to a serious circadian misalignment. Now, research links chronic circadian disruption with a much higher risk of metabolic disease, sleep disorders, mood disturbances, and several chronic conditions. And this is why managing your light exposure is, without doubt, one of the most powerful tools that a shift worker has. So let's go through some simple principles for managing light. The biology here leads to some simple but very important principles. First of all, we can offset light at night by getting bright, natural light early in the day whenever possible. So resetting that circadian clock to the early in the daytime and getting that bright light so that it anchors that circadian rhythm. Outdoor daylight is far stronger than indoor lighting. And I want to make this quite clear as well. Those lights inside your house, those circadians, those LEDs, those low voltage LED lights, and the lights that are generally on in your house, they don't have the correct spectrum of light. They've got insufficient blue in them. They're dull. They don't reset your circadian rhythm. While there's light, there is insufficient blue to actually trigger the cells. Internal light runs at about 500 lux of light. When you step outside, even on a gloomy and overcast day, you're getting about 10,000 lux of light. So it is far more activating. Even on an overcast day, you're still getting the full spectrum of color of light. You're getting infrared, ultraviolet, yellow, blue, green, red. You're getting all of those colors. Orange, the

Simple Rules For Managing Light

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whole lot. Even though you see it as white, you're getting all of those. And the benefits of this is enormous to your health. And this is why I say to people get sky before screen. Now, what we've got to do also is we've got to reduce this bright and blue enriched light in the evening. We need to lower our lights right down. We need to use warmer light tones. We need less screen exposure before bed. And third, we must protect complete darkness during sleep. A dark sleeping environment helps melatonin remain elevated during the night. This is why I say when you lie in bed, hold your arm out at a full length and turn your hand to face your face. And if you can see your hand, it is not dark enough. And that is where you need to be using a sleep mask. Vital. Not just, oh, it's dark enough or it's a little bit dark or it's okay or whatever. No, it needs to be fully dark. Otherwise, your eye registers blue and you won't sleep properly. Now, for shift workers, targeted light exposure during work combined with darkness during daytime sleep can actually help to stabilize the system if you get this all right. And I can help you with that. And this is what I do in my one-to-one coaching is to help people with circadian alignment. So let's go through the key idea. And the key point is simple. Light is not just something we see, light is information to our body. Because when light enters your eyes, those IPRGC cells measure it and then send that information back to the brain's clock. The brain then adjusts the hormones, the metabolism, the alertness, and the repair processes to match the time of day. So that light environment that you live in is constantly shaping your biology, not just your vision, your entire physiological rhythm. Now, let's go back to my opening statement that blue light does not inhibit you going to sleep. Research shows that it is clear that blue light at night only really inhibits sleep latency by about seven minutes. And that is not statistically significant. So if I said to you, you can look at your phone at night, no problems, because it's only going to inhibit your sleep by about seven minutes, you would take looking at your phone all day, every day. I know you would because that's what you do. But I will forewarn you of this, and let's be very clear on this point. That phone is putting blue light in your eye.

Light Is Information For Biology

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There is a massive difference between falling asleep exhausted and falling asleep because melatonin has elevated in your body, and you're going to get good, solid, restorative sleep with elevated melatonin, which is going to help with eradicating those free radicals in your system. Well, you can look at your phone in bed and you can get that blue light into your eye, and you may still roll over and go straight to sleep because. Research tells us that you can. The biggest problem that you've got is it's face shifted your circadian

The Blue Light Claim Resolved

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rhythm, and that blue light going into your eye has suppressed melatonin. So your body is not getting that signal of darkness. So don't ever wonder why it is that you can go to sleep, but then you wake up at two o'clock or three o'clock and you can't go back to sleep. Don't ever wonder why you wake up and you still feel tired. That is circadian misalignment, and that is caused by you looking at your phone in bed. So while you can go to sleep because you are exhausted, that is adenosine. That is making you go to sleep. But the blue light hitting your um IPRGCs in your eye has actually literally face shifted your circadian rhythm and suppressed your melatonin, leaving you wide open for cancers and all of the metabolic diseases that circadian misalignment brings. So be very careful. Scrolling in bed at night might seem fun and it might you might find it relaxing, but it's actually slowly killing you. And it's that simple. Most people never think about this. They just look at light about the brightness and the visibility of it. But inside your eye is a very complex system which is designed to read the light of the sky and to set the timing of your body. Morning light tells the brain that the day has started. It suppresses sleep, it fires you up to get you going. Darkness allows melatonin to rise, and that nightly rise helps to drive the repair and the protection that your body needs. So let the question become this simple. Are you giving your body the right light signals at the right time? Because those signals quietly control far more of your health than most people realize. Don't tell me your hormones are stuffed while you're looking at light at night. Thank you for listening. If you enjoyed this episode, be sure to subscribe so you get notified whenever a new episode is released. It would also be ever so helpful if you could leave a rating and review on the app you're currently listening on. If you want to know more about me or work with me, you can go to ahealthyshift.com. I'll catch you on the next one.