Chapter Content
Okay, so, like, hey everyone. I wanted to talk about something really important today, and it's all about, uh, respecting your body's clock, your biological clock. Yeah, and how light, sleep, and when we eat all, like, really tie into that.
You know, I remember once, back when I was a resident... it was intense. I was, like, on call, which basically meant I was the only surgeon awake covering everything. I had already been up for like, a full day, right? And I was trying to grab, like, five minutes of sleep when my pager just *buzzes*.
I walk into this OR and there are, like, fourteen doctors and nurses running around like crazy! There’s this woman on the table, her neck is totally... open. She'd been stabbed, you know? And I'm in there, looking for, like, any major vessel tears that need fixing. And, like, I'm totally focused, minutes pass, and then I look up and everyone is just... stopping. Stepping away. She, uh, she didn't make it.
I was thinking, wow, this woman was just attacked, you know? So violent and so scary. And I consider myself a very empathetic person, I won an award for humanism, my house is filled with self-help books. All I could think about was getting to sleep! Seriously.
I called my supervising doctor to tell him what happened, and he just, like, cut me off and yelled, "Are you seriously waking me up to tell me about a dead person?" and hung up! I was shocked. But I get it now, he was exhausted too, right?
Looking back at those residency years, it was, like, a blur. Windowless rooms, stealing sleep when I could, just grabbing whatever packaged food I could, any time of day. And I learned later, these sustained disruptions, they can actually cause measurable brain damage, problems with your emotions, metabolic issues, even memory problems!
Okay, so, residency's an extreme example. But in a lot of ways, our modern lives mess with our natural rhythms. We're not sleeping or eating in sync with how our bodies are really designed to work. And that can cause problems.
I mean, think about it. In the last hundred years, we're sleeping, like, 25% less on average. And we only had artificial light for, like, a tiny, tiny fraction of human history, right? Now, we sit indoors, under artificial light, all day, and we're just cut off from the sun and the earth.
I'm not saying we need to go back to prehistoric times! But we need to appreciate how new and, well, biologically disruptive, these inventions actually are. They're super-connected to our mental and physical health.
See, over millions of years, we've developed really complex, internal clocks. Clock genes, specialized brain regions that respond to light. And while our cells have their own little clocks, they need to synchronize with external light cues. The timing of when we're exposed to light, and when we're exposed to food, these are really important. Our chronobiology controls everything, like when we wake up, when we eat, how our genes are expressed, when we should sleep.
Humans are diurnal, meaning we're supposed to be active and eating when it's light, and sleeping and fasting when it's dark. But in the modern world, we've totally messed that up. We're eating late, we're looking at screens late, it's just cellular confusion. And that can lead to those symptoms and diseases a lot of us are dealing with.
Research shows that these erratic sleep, light, and eating schedules can directly lead to mitochondrial dysfunction, oxidative stress, and chronic inflammation. And, you know, a lot of people just don't think about their circadian rhythm, but we really should.
If a car battery needs eight hours to charge, you wouldn't charge it for six and expect it to go further, would you? Well, that's kind of what we're doing to our cells. We're messing up the schedule that our bodies are designed to run on. Then we wonder why we feel so bad! We need to understand the schedule our cells are wired for, how profoundly important it is for our energy levels.
And it comes down to sunlight, sleep, and when we eat.
We're made of sunlight! It's not a metaphor, really. Almost all the energy we get from food comes from the sun, right? Remember photosynthesis? The sun’s energy gets stored in glucose molecules in plants. Even if you eat mostly meat, those animals were often herbivores! And photosynthesis creates oxygen.
The sun’s why we have life on Earth! And we need to know the three ways it's crucial to our bodies.
So, a regular pattern of sunlight and darkness has been driving our biology forever. Our cells are encoded to be on a twenty-four-hour sleep-wake cycle, in two modes: activity-feeding mode during sunlight, and resting-starvation mode during darkness. And light exposure dictates which mode we're in. Giving the body mixed signals leads to dysfunction.
Sun entering our eyes is the body's "on" switch. The amount of light we get outside is way more than inside with artificial light. Even sitting under a tree, you're getting way more light than indoors. Glass can block photons, which is how our cells know what time it is. Modern kids just don't spend enough time outside experiencing higher levels of light.
When light hits our eyes, it triggers an electrical impulse. That leads to the brain's suprachiasmatic nucleus, or SCN, which is like a master conductor of our body's functions. Those optic nerves are waiting to transmit that light signal to turn "on" the body’s biology in the morning. But modern living prevents us from spending much time outdoors in the morning.
So, while the SCN has its own internal pattern, light synchronizes our cellular clocks, telling the body what time it is, releasing hormones and genetic processes that control everything: energy production, melatonin release, digestion, hunger, stress hormones.
Irregular light, experiencing light at night, being indoors during the day, can disturb our metabolism and increase the risk for health problems.
More light in the morning and less at night signals to the SCN what time it is, it sets our bodies up to time genetic and hormonal signals properly. Key way to regulate your hormones, metabolism, weight, and risk for disease is by showing your cells what time it is. Expose your eyes to sunlight throughout the day, and hide your eyeballs from as much light as possible when the sun's down.
Experts have known for decades that insulin sensitivity and glucose tolerance go through a daily cycle. Bright light during the day is crucial for maintaining insulin sensitivity. Some studies even showed that minor changes in light exposure can have a significant impact on insulin resistance. This might explain why people exposed to light at the wrong times are more likely to develop metabolic disorders.
Also, sunlight impacts our mood. Less sun exposure can trigger depression. Research connects reduced sunlight exposure to lower levels of serotonin, which regulates mood. Natural light can enhance serotonin. Increased serotonin can reduce appetite and improve glucose control. So, yeah, sun can make you happier.
Now let's talk about sleep.
Want to give yourself prediabetes? Sleep only four hours a night for six days! Every time you skimp on sleep, you generate oxidative stress, mitochondrial dysfunction, chronic inflammation, and microbiome dysfunction! You could eat perfectly, but if you don’t sleep, your cells will, like, throw off excess free radicals, send danger signals, and struggle to make energy, and become insulin resistant. Lack of sleep is a huge danger signal to the body.
And lack of sleep creates a vicious cycle. Bad energy makes it harder to get good sleep, which then makes the bad energy worse. You have to break that cycle. Poor sleep is a modern, pervasive thing, and it's bad news!
Sleep affects everything: mitochondrial dysfunction, oxidative stress, chronic inflammation, your microbiome.
One study even showed that long-term sleep deprivation destroyed the structure of mitochondria in mice! Which led to heart failure! Other research shows sleep deprivation decreases activity in the mitochondrial electron transport chain.
Sleep deprivation increases free radicals and oxidative stress all over the body. Researchers think that sleep helps neutralize free radicals accumulated during the day.
Even a little sleep restriction, just six hours per night for a week, can increase pro-inflammatory chemicals in the blood, which induces insulin resistance.
Sleep deprivation can change microbiome composition, which researchers think mediates the negative effects like chronic inflammation.
In humans, there's a tight link between sleep deprivation, gut dysfunction, and oxidative stress. Sleep restriction decreases the gut bacteria that produce butyrate, which fuels gut cells and impacts energy metabolism. A healthy gut barrier protects against chronic inflammation. A lack of sleep messes with our gut microbiome. We need to sleep for ourselves and our microbiome!
And sleeping too little will make you overeat. It alters hunger and satiety hormones. You get an elevation in the hunger hormone ghrelin and a decrease in the satiety hormone leptin. And it increases your appetite for calorie-dense foods. If you want to protect against overeating, sleep.
People say the causes for the increase in obesity are complicated. It’s infuriating. The main causes are the explosion of highly processed food and the erosion of healthy sleep.
Okay, so sixteen hours of no sleep starts physiological deterioration, it gets worse from there.
Lack of sleep impairs cognitive ability. A study showed that participants with four hours of sleep for six nights experienced a 400 percent increase in microsleeps during the day. Microsleep is a period of no response during a task, and participants didn't even realize they were happening!
Doctors are some of the most sleep-deprived people out there, and they receive very little education on sleep. But good sleep is one of the most effective tools in preventing and reversing all kinds of diseases. Everyone should prioritize quantity, quality, and consistency of sleep like their life depends on it.
We need to get seven to eight hours a night of good-quality sleep to protect ourselves. Studies show that sleep deprivation decreases ATP production in the brain. We all want a brain with less energy, right?
People who sleep less than 6.5 hours per night have to produce 50 percent more insulin than normal sleepers. And prediabetes and type 2 diabetes are insulin resistance.
Just a couple of nights of low sleep can severely impact insulin sensitivity. One study showed that sleep deprivation made young men exhibit glucose responses characteristic of prediabetes.
Cortisol tells our body that something stressful is happening. Chronic cortisol stimulation, like from chronic sleep deprivation, decreases insulin sensitivity, elevating blood glucose levels and fueling inflammation.
So, that "magic number" is seven to eight hours of sleep.
Kids with truncated sleep from early school start times, it’s setting them up for a lifetime of metabolic illness. They experience higher insulin levels, insulin resistance, higher fasting glucose, and higher BMI. Insufficient sleep increases a young child’s risk of obesity later.
Also, minimally interrupted sleep is important. Reduced sleep quality is linked to conditions like type 2 diabetes, obesity, heart disease, and Alzheimer’s disease.
One study showed that people who reported difficulty maintaining sleep had a higher risk of developing type 2 diabetes. Also, the better sleep quality a person had, the more likely they were to have a lower blood glucose response to breakfast the next morning. Poor sleep quality can affect glucose responses by changing cortisol and growth hormone levels.
You can assess sleep quality by looking at the amount of time spent in deep and REM sleep, which are metabolically restorative. Recent research showed that mortality was 13 percent higher for every 5 percent reduction in REM sleep. The goal is at least 15 percent or more REM sleep per night.
It's really important to keep a consistent bedtime. Research has found that social jet lag, which is a measure of sleep consistency, doubles the risk of metabolic syndrome and diabetes. Almost half of US adults report at least one hour of social jet lag.
These shifts are associated with increased heart attack, stroke, hospital admissions, emergency room visits, car crashes, and mood disorders.
We ignore the science of circadian clocks at a societal level, especially when it comes to kids. Teens naturally want to stay up later and sleep in longer, but schools have early start times. Insufficient sleep can lead to insulin resistance, weight gain, and an increased risk of type 2 diabetes.
And delaying school start times to match teenagers' natural circadian rhythms can have benefits.
Okay, so, we've all heard artificial light can mess with sleep. It's because light at night signals to your brain that it's daytime when it's not. It's now considered an "environmental endocrine disruptor," meaning it can directly alter hormone signaling. It can change melatonin production, increase inflammation, and elevate stress hormones. Artificial light at night can help explain excessive body mass worldwide. Light in the evening is associated with increases in insulin resistance and glucose levels. Exposure to indoor room light as opposed to dim light before bed causes later melatonin release. Some of the functions of melatonin include inducing sleep, suppressing cancer, supporting bone health, and acting as an antioxidant. Given all this, disrupting melatonin with excessive artificial light at night is, like, a big deal.
Even ambient light in our bedrooms has an effect. Light while sleeping is associated with a higher BMI, higher waist circumference, and higher waist-to-hip ratio.
Let's talk about meal timing.
When we eat during the dark period of the twenty-four-hour cycle, we experience desynchronization of our metabolic processes. In animal studies, when mice are fed their normal diets during the time when they’re meant to be asleep, they rapidly gain weight.
Our bodies are primed to be more insulin sensitive and generate more heat from metabolizing food in the morning instead of the evening. We do much better by eating more of our food earlier, and especially higher carbohydrate foods, and stopping eating as early as possible in the evening. Eating later in the evening causes a significant increase in both insulin and glucose levels compared with eating the same meal in the morning.
But, modern Americans, only 25 percent of our food intake happens before noon, and 35 percent happens after six PM. We have erratic food patterns and ultra-frequent food intake. And all this predisposes us to metabolic dysfunction.
Instead, try to eat at consistent times, and cut off the last food intake earlier in the evening. It's called time-restricted feeding, or TRF. Even just four days of TRF can considerably reduce fasting glucose, fasting insulin, and mean glucose levels.
TRF is under the umbrella of fasting, which is an intentional restriction of food. It has been part of our history and biology. Our bodies are primed to function well when we flip-flop between eating and not eating.
The two primary fuel sources for your cells are glucose and fat.
Glucose, which is circulating in the bloodstream, is more readily accessible for energy. Fat is a long-term energy storage source.
But most of us are in a constant fed state, fueled by glucose, from breakfast till dessert at night. We keep our bodies in glucose-burning mode and deprives us of the benefits of utilizing fat.
When people are hungry after not eating for a few hours, that likely reflects metabolic inflexibility: a problem switching from glucose burning to fat burning. It's linked to metabolic syndrome, type 2 diabetes, and chronic inflammation.
Fasting lets your body practice switching between burning available carbohydrates and glucose and burning fat for energy. Insulin promotes fat storage and restricts fat breakdown, so when we fast, we allow insulin levels to fall and let fat get mobilized. Fasting is also a stressor on the body. No matter which fasting style you follow, you should try to reduce your daily eating window to avoid food in the late evening, and try to eat your last food before dark as often as possible. This tweak alone will be life-changing.
Unfortunately, our Western cultural norms are, like, totally opposed to optimizing our biological rhythms. You need to take things into your own hands and be a counterculture circadian warrior in your journey to good energy. It's hard, but the other side is better mental and physical health.
If things are preventing you from getting enough sleep, you need to fix them. I mean, really! If a pet is jumping on your bed, preventing you from sleeping through the night, you should consider training or rehoming your pet. If your partner snores, they should address the problem, or consider earplugs or sleep in a different room until it's resolved.
And, you know, I know a lot of people would sleep more, but they have trouble sleeping! So, you're not alone! Bad energy leads to insomnia. A high intake of ultra-processed foods contributes to metabolic issues, which also contributes to insomnia. Artificial light contributes to both, you know. Chronic stress, late-night eating, it's all connected.
Good energy results from good sleep, but also food, movement, stress management, and toxin avoidance. So if sleep's a struggle, start with the other pillars of good energy, and you may find that sleep gets easier. That creates a positive cycle, you see? And the first thing that helps you with getting good sleep and having good energy is to spend more time outdoors during daylight hours!