Chronobiology And Your Health

Chronobiology And Your Health

Chronobiology And Your Health


Ever wondered why you’re a night owl, but your friends are passed out by 10:00 every night? Thank you circadian rhythms. These built-in clocks are wired within each of.  Learn about chronobiology and your health in this post.

Chron·o·bi·ol·o·gy
[kron-oh-bahy- ol– uh-jee] – is the science or study of the effect of time, especially rhythms, on living systems. (Definition taken from Dictionary.com).

Circadian Rhythms And Health

The 24-hour cycle we are all familiar with is based on the earth’s rotation and solar and lunar rhythms. These biological rhythms are inherent in each of us including plants and animals.

Although, there are other rhythms that fall under the heading of Chronobiology, in this post I will be discussing circadian rhythms.  Their effects on health have been researched the most extensively.

What Are Circadian Rhythms?


Circadian rhythms are internal clocks, based on a 24-hour cycle, that tell us when to rise, when to eat, and when to sleep. They regulate many  processes in the body. The liver also plays a role in these rhythms via the proteins, AMPK and CK2, which are involved in metabolism, energy production, and cell division.

The hypothalamus is the head honcho when it comes to circadian rhythms. Glands are involved, as well, including the pineal, thyroid, and adrenal glands. Their production of hormones are regulated by sleep/wake cycles.

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Circadian clocks not only regulate hormone production and eating and sleeping patterns, but also brain wave activity, urine production, and cell regeneration. Cortisol and melatonin are the two hormones most affected by circadian rhythms, and oppose each other. When cortisol levels are high in the morning, melatonin levels are low, and as cortisol levels dip throughout the day, melatonin starts to rise as nighttime approaches. Melatonin lowers body temperature in preparation for sleep, and cortisol regulates blood sugar in order to stimulate alertness. Cortisol also controls inflammation.

Many physiological processes are involved, including organ function. Although these internal biological clocks are generated endogenously, they’re kind of like genetic-time clocks, and can be affected by external factors such as sunlight and temperature. An awareness of how circadian rhythms work is important because they can be influenced by lifestyle factors.

Chronobiology And Your Health

How Do Circadian Rhythms Affect Health?


These natural rhythms are important because not only do they affect sleeping cycles, but also temperature regulation and even digestion. If these internal clocks are out of sync, the risk of chronic health problems increases.

Ask any new mother how the lack of her baby’s circadian rhythms are affecting her health, and you’ll probably get an earful. As we all know, it takes awhile for babies to establish circadian rhythms, and what a relief it is when they do!

Apparently, it’s common for blind people to have sleep problems as light is a predicting factor in establishing consistent rhythms.

Think of college students pulling all nighters before an exam. Following the exam, they may, fairly predictably, come down with a virus due to their immunity being affected from circadian disruption. Or have you ever returned from vacationing, and come down with the flu?

You Have Most Likely Noticed These Rhythms

Have you noticed that you are more productive in the morning? You have the energy to exercise or write or whatever else needs to be done. You’re able to plow through tasks with ease because your energy levels are high. But what if you had to exercise at night or finish a project? It’s highly likely you won’t be as productive.

Then there’s the infamous slump that happens around 3:00 or 4:00 in the afternoon. Anticipate this happening, and take a few minutes to catch up on tasks that don’t take a lot of mental prowess. This is honoring your internal clock. Or take a relaxing stroll for ten minutes if you can to combat mental sluggishness.

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When would be a more effective time to train for a marathon? in the morning or at night? I think I’ve made my point. Work with you internal clock instead of against it.

If you’ve ever thought of calling a friend to chat at 6:00 p.m., you might want to re-evaluate. The chances of them being in the mood to talk will be slim if they are just getting home from work, making dinner, have cranky kids, or just need some downtime to absorb the events of the day. However, this same friend may love to talk on their lunch break when their cortisol levels aren’t so low!

Our circadian rhythms can also ebb and flow on a weekly basis as most people can attest to.  Friday afternoon burnout is a real phenomenon.

How Internal-Clock Disruption Can Affect Weight


Circadian clocks can impact weight. Consistent sleep/wake cycles and meal planning can go a long way toward good hormonal balance. Chronic sleep deprivation causes insulin resistance, and eventually, type 2 diabetes.

The “hunger hormones” leptin, ghrelin, and adiponectin fluctuate throughout the day, around meal times, and are influenced by sleep deprivation.

– Leptin, made by fat cells, decreases appetite, and is called the satiety hormone.

– Ghrelin, produced in the stomach, increases appetite, and stimulates hunger. This hormone increases on low-calorie diets.

– Adiponectin is also made in fat cells. The more of this hormone that your fat cells make, the leaner you’ll be. It burns fat and regulates blood sugar. The less adiponectin you make, the easier it is to gain weight.

You want these weight-regulating hormones working with you, as they have the important task of regulating metabolism and appetite. If they are imbalanced, you won’t get the signal to stop eating when you are full.

And then there’s insulin and cortisol that are regulated better in the evening – you can get away with eating more carbohydrates at dinner.

Factors That Interfere With Circadian Clocks


  • Flying at night
  • Traveling over time zones
  • Pulling all-nighters
  • Shift work
  • Not having regular meals
  • Daylight Saving Time

Many factors disrupt natural rhythms, and are not without cost, especially if prolonged. Metabolic syndrome, as well as, type 2 diabetes can be caused  from disrupted circadian rhythms. The stress hormone, cortisol, can be affected also, leading to problems with blood pressure and blood sugar. Mood disorders worsen or arise if rhythms are disrupted for too long. Metabolism and immunity also suffer.

How To Reset Biological Rhythms


1. Develop consistent eating and sleeping schedules. Consistency keeps our internal clocks ticking smoothly.

2. Bright light in the morning suppresses any residual melatonin and increase alertness.

3. Use yellow light bulbs in your lamps, instead of regular bulbs. They won’t interfere with melatonin production.

4. Nightshift on iPhones is very helpful as it shifts the natural blue light on your phone to a lovely yellow glow. If you read books on your phone or watch movies in bed, the ability to fall asleep won’t be hindered.

5. If your family has bright lights on – like mine does – in the evening, wear blue-blocker sunglasses a couple of hours before bed. The natural increase in melatonin, as the evening progresses, won’t  be affected.

6. Light therapy in the morning can stimulate cortisol, and increase alertness, and also alleviate seasonal affective disorder.

7. Taking a melatonin supplement at night can be helpful, especially when traveling, to combat jet lag.

8. Exercising too close to bedtime may interfere with cortisol levels and impair sleep.

9. Sleeping on a latex pillow has really helped to improve my quality of sleep, and I take it with me when I travel to cut down on jet lag.

You likely won’t be aware of circadian rhythm swings if you have been getting adequate sleep, however, if you are chronically sleep deprived, you’ll be more likely to notice the natural ebb and flow of mental alertness and drowsiness.

Natural rhythms can change with the seasons and throughout the life cycle. In the winter, when it gets dark earlier, people are typically more tired in the evening, and we’ve all noticed that teenagers need more sleep than do older people.

Final Thoughts


Circadian rhythms are wired into all of us. Creating an awareness around them promotes healing.

These internal clocks respond to external cues, so we can in part, control them.  Identify the routines that make you feel well, and stick to them. Let’s honor our circadian rhythms!

What are your thoughts on circadian rhythms? Please leave you questions and comments below.

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