Circadian Rhythms Affect Digestion, Heart, and Lungs

by
Filed Under: General Health
Last Reviewed 02/06/2014

Circadian Rhythms Affect Digestion, Heart, and Lungs

Hundreds of body functions are tied to the circadian rhythm

One topic that has always fascinated me has been the circadian rhythm, or the body’s built-in biological clock. Practically all of the animals and plants on Earth run on this invisible 24-hour clock—give or take an hour, in the case of some individuals.

Although the research data seem to be poorly compiled, if you search hard enough, you’ll find that hundreds of body functions have been linked to the circadian rhythm, including your digestion, your heart health, and your respiratory system.

Go With the Flow

Circadian rhythms are not a new discovery. The Chinese diagnostic and healing technique of acupuncture has used much of this information for thousands of years. It’s astounding that the Chinese were able to figure these things out without the benefit of blood or urine tests or many of the tools we now have at our disposal.

I don’t want to get too detailed about acupuncture here, but if you understand a few concepts associated with it, you’ll be able to see why circadian rhythms can be a useful tool.

According to many types of Oriental medicine, an energy called chi (pronounced “chee”) flows through every living thing. In the human body, chi flows along 12 main routes, or channels, called meridians. For purposes of illustration, picture chi as a ball of energy that enters one end of a meridian and continues along that meridian until it exits the other end, where it enters yet another meridian. This ball of energy keeps moving from one meridian to the next until it has passed through all 12, and then repeats the cycle. Chi takes two hours to pass through each meridian, and the entire cycle takes 24 hours.

Although a meridian always contains a certain amount of energy, its energy levels peak during the two hours the chi is passing through. Each meridian has its lowest level of energy 12 hours later. According to traditional Oriental medicine, the lung meridian has its peak energy from 3–5 a.m. every day. Its lowest energy level would be exactly opposite, from 3–5 p.m., when the bladder meridian would be experiencing its peak energy. (In acupuncture, this is called the Midday–Midnight Law.)

Practitioners of Oriental medicine knew that problems in various organs most often occurred when their energy levels were either at their highest or their lowest. Thousands of years later, researchers are beginning to find the same thing.

Put Asthma Problems to Rest

In the example above, the lung meridian has its peak energy from 3–5 a.m. Researchers have found that around 4 a.m., the adrenal hormones, adrenaline (or epinephrine) and cortisol, are at their lowest levels. These adrenal hormones are higher during waking hours to help regulate blood sugar levels, and are the same ones associated with the “fight or flight” mechanism. These hormones also relax the airways, making breathing easier.

From 4–6 a.m., when these airway-opening hormones are at their lowest levels, asthma attacks occur at a rate 100 times more often than at any other time of the day. Although there are numerous triggers for asthma attacks, research has shown that a high percentage of asthma sufferers experience breathing difficulties at night, and the majority of severe asthma attacks that result in death occur between midnight and 6 a.m.

Based on these findings, doctors around the world have seen improved results when they have their asthma patients take steroid medications in the early afternoon and their theophylline in the evenings. (I’m not recommending that anyone change their medication routines without the guidance of their doctor. There are numerous forms of these medications, and they all work differently.)

Your Heart Fears Your Alarm Clock

The whole process of awakening from a night’s sleep is fraught with potential problems. Blood chemistry changes rapidly. As your sympathetic nervous system kicks in, it triggers increases in cortisol, cathecholamines, serotonin, renin, aldosterone, angiotensin, and free radicals. These restrict blood flow, increase blood pressure, and set the stage for more serious consequences.

Based on studies of the circadian rhythm, we know that the greatest risk of heart attack and stroke occurs in the hours just after awakening. According to Oriental medicine practitioners, the peak energy level in the heart meridian occurs between 11 a.m. and 1 p.m. Research shows most cardiovascular events take place between 6 a.m. and noon. This has been substantiated throughout numerous studies.

Researchers from Harvard Medical School reviewed more than 30 different studies over a 10-year period covering over 66,000 heart attacks. They found that 19,000 heart attacks, all of which resulted in sudden death, occurred during the morning.

Blood pressure shoots up again, even more rapidly, when you get out of bed and begin moving around. An instant demand is placed on the heart, which in turn requires additional oxygen. Platelets are stickier and more prone to clot and cause blockages in blood flow. If you’re like the large majority of individuals in the U.S., you have some degree of atherosclerosis, or clogging of the arteries, which increases the risk of early-morning stroke or heart attack. Circadian research has found that more than half of all transient ischemic attacks (TIAs) also occur between 6 a.m. and noon.

Keep Your Digestive Tract Ticking Around the Clock

Peak energy level for the stomach occurs from 7–9 a.m. and there have been numerous explanations for this. One explanation is that breakfast is the most important meal of the day. By sending the peak amount of energy (in the form of food) to the stomach at that time, digestion, absorption, and energy levels are all improved. Unlike the other organs we’ve looked at so far, most of the problems with the stomach occur when its energy level is at its lowest.

Everyone knows that the stomach secretes digestive acids with every meal, but few realize that from 10 p.m. to 2 a.m., it secretes two to three times more acid than at any other time. Why this occurs is still somewhat of a mystery. Some researchers think it may be part of a cleansing process that helps destroy any residual pathogens. No one is sure. What is certain is that nighttime acid production causes a great deal of distress for many people, particularly older adults.

Nighttime heartburn, or gastroesophageal reflux disease as it is often called, occurs when acid, which should remain in the stomach, “leaks” into the esophagus.

Suggestions such as not eating late meals or immediately before bedtime will often help, as will using blocks or bricks to raise the head of your bed 4–6 inches. I have found that including digestive enzymes or enzyme-rich foods, such as a slice or two of pineapple, with the evening meal can also help. By improving or speeding up the digestive process, there is less chance that acid-laden undigested foods will later seep into the esophagus.

The field of circadian research, chronotherapy, body clock rhythms, or whatever you want to call it, can provide valuable insight into how we help restore and maintain our health. I find it fascinating, and I’ll continue to pass this type of highly useful information along as it becomes available.

Related Articles & Categories
Enjoy What You've Just Read?

Get it delivered to your inbox! Signup for E-News and you'll get great content like you've just read along with other great tips and guides from Dr. Williams!