Circadian rhythms are physical, mental, and behavioral changes that follow 24-hour cycles that are part of the body’s internal clock. They are always running in the background to carry out essential functions and processes. They can influence hormone release, eating habits, digestion, body temperature, and of course sleep.
Different systems of the body follow circadian rhythms that are synchronized with the master clock in your brain. Your master clock is directly influenced by environmental cues, especially light and day, which is why circadian rhythms are tied to the cycle of day and night and sleep and awake.
Research has shown again and again that when properly aligned, a circadian rhythm can promote consistent and restorative sleep, but when thrown off, can cause insomnia, as well as physical and mental health problems, because they coordinate our physical and mental systems throughout the body.
Your master clock, which is located in your brain, uses light to coordinate all your internal clocks, as well as exercise, social activity, and temperature. At different times of the day, it sends out signals that regulate activity throughout the body.
When we talk about circadian rhythm, we’re usually talking about sleep. The sleep-wake cycle is one of the most clear and critical of circadian rhythms and is directly linked to your longevity and health span.
During the day, light exposure causes your master clock to send signals that generate you to be alert, awake and active. At night, it starts the production of the sleep hormone melatonin, and, once you’re asleep, it keeps transmitting signals to keep you asleep through the night.
There are other 24-hour internal clocks that play a vital role in pretty much all of the systems of your body – metabolism and weight through the regulation of blood sugar and cholesterol, mental health, your immune system and even DNA repair.
When your circadian rhythm is thrown off, it means that the body’s systems don’t function optimally. And, when your sleep-wake circadian rhythm is thrown off you can develop serious sleep problems such as sleep apnea, but can also affect your overall health and, of course, your aging process.
A recent study shows that animals that are exposed to artificially shortened or lengthened periods of daylight have shorter lifespans, and another study shows that when humans are restricted to five hours of sleep for four nights, they begin to develop insulin resistance and prediabetes.
To keep your circadian rhythm healthy, it’s important to get exposure to natural light early in the day as well as at times during the day; follow a consistent sleep schedule, even on weekends, vacations and holidays; get daily exercise; avoid caffeine and limit your exposure to artificial light after sunset.
Humans have receptors in our eyes that process blue spectrum light, and this tells our bodies to stay awake and be alert. Before televisions, cell phones, computers and tablets, the only blue light that we were exposed to was from the sun during the day, and this is what our bodies evolved to use to set our circadian rhythms. So, when you use screens at night, this messes with your circadian rhythm, and it even messes up your gut flora which, as we already know, leads you to age more rapidly.
New research shows that your gut microbes have a rhythm as well. They begin their day in one part of the intestine, and move a few micrometers, and then return to their original position. As they day goes by, disruption of this movement can affect the way we sleep.
Multiple studies show that sleeping has a direct effect on your inflammatory signaling and that less sleep results in daytime inflammation, which in turn affects our immunity. If you’ve ever noticed that you get sick more often when you’re sleep deprived, now you know why.
Being deprived of sleep can leave you more susceptible to infections, and, unfortunately, to chronic inflammation, which can lead to a whole host of those illnesses that we associate with normal aging, but they’re not.
Eating also can affect your circadian rhythms. Your metabolism peaks around lunchtime and then begins to slow down, after lunch, as the day progresses, you don’t break down calories as efficiently, this in turn, causes weight gain.
If you have trouble sleeping, it’s best to eat your biggest meal at lunch, have a snack for dinner, finish eating at least 3 hours before you go to bed.
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