About circadian rhythms

Circadian Rhythms are our body's natural cycles that control appetite, energy, mood, sleep and libido. Almost all of us, at some time during a year fall out of balance and suffer from sleep or mood problems. Fortunately, after decades of research, science has found the way to create circadian balance.

Nature's rhythms

Much of nature is made up of rhythms or cycles. Common rhythms include the four seasons and the twenty-four hour rotation of the earth. Like nature, our bodies have rhythms. Some of the rhythms of body and mind are tied to nature. When working properly, our bodies respond to nature's cues to create their ideal rhythms. For example, when functioning properly, the human circadian rhythm will respond to the morning light of a new day. This light will cue the body to produce cortisol, serotonin, and other hormones and neurotransmitters that get a person awake and going and cause blood pressure to increase and body temperature to rise.

At sunset, the body receives another of nature's cues and responds to dusk and ultimately the night's darkness. As the sun goes down the body will produce and secrete the hormone melatonin, and blood pressure will drop as the body prepares for and eventually falls off to sleep.

In reality circadian rhythms control the timing, quantity and quality of the hormones and neurotransmitters the body produces and eventually secretes. Hormones and neurotransmitters are the elements that determine how we feel, our sleep patterns, our appetite, our sex drive and other sleep and mood-related issues. When functioning properly, our circadian rhythms create circadian balance. When out of balance, quantity, quality and timing of hormone and neurotransmitter secretion suffer and our bodies may begin to suffer from a circadian rhythm disorder (CRD).

The master clock

Significant progress is being made in the field of chronobiology, the formal name for the medical science that studies circadian rhythms. Researchers have discovered that the human body is orchestrated by internal biological clocks marching to several internal rhythms that pace themselves hourly, daily, monthly, seasonally and even yearly.

Central to the timekeeping mechanism of the body and mind are Suprachaismatic nuclei or SCN. The SCN is the master clock - the circadian rhythm that controls all other rhythms of the body. The SCN is actually two clusters of 50,000 neurons, one on each side of the brain. The SCN sits inside the hypothalamus region of the brain and works with several time keeping genes. Together, the SCN and the timekeeping genes make up the central clock which governs many aspects of physiology and behavior because they orchestrate the daily rhythms and cycles that control the ebb and flow of hormones, chemicals and neurotransmitters that determine wake, sleep, appetite, sex and other key aspects of our lives. It is vitally important to understand the SCN and to how to care for it.

Circadian science

The study of circadian rhythms dates back to the 19 th century. However, significant studies and observations began in earnest in the 1960's. One early pioneer was Curt Paul Richter, a professor of psychobiology at Johns Hopkins Medical School whose innovative concepts are the foundation for established concepts and methods for studying circadian rhythms in humans.

The word circadian is Latin in origin from the word circa meaning "about" or "approximately" and dian meaning "day". The term circadian was coined when Franz Halberg, a scientist at the University of Minnesota, published a paper in 1959 showing blood count varied according to a strict rhythm that was about a day. In fact, Halberg discovered that the rhythms actually went somewhat longer than a twenty-four hour day.

The field of chronobiology, the medical discipline that studies circadian rhythms, has since revealed that the body undergoes more than just blood count variations. In fact, the body makes significant changes throughout a day.

Human's free-running rhythm

Beginning in 1980, several studies were conducted to learn more about the human circadian rhythm. These studies included placing people in an isolated environment without any external cues or clues as to what time it was. These studies conclude that, if left alone, healthy humans undergo changes based on an internal clock that is longer than twenty-four hours. These changes in biological rhythms can be measured in physical strength, aerobic capacity, body temperature, blood pressure, mental alertness, production and secretion of neurotransmitters & hormones, and many other body functions.

No one knows for sure why the cycle is more than twenty-four hours as opposed to precisely twenty-four hours, nevertheless, herein lies part of the problem. If the internal circadian clock of an individual is "free-running", (a state in which the body is not receiving external signals or cues) it is only a matter of time before lifestyle realities clash with free-running circadian time. This clash means hormone and neurotransmitter secretion becomes confused and will create problems for their health.

Zeitgebers: the body's way of synchronizing

In order for to reconcile the difference between natures exact twenty-four hour cycle and the internal circadian rhythms we free-run on, nature has given us "zeitgebers", a German word that means "time givers". As modern lifestyles demand more flexibility in schedules, man has lost touch with its most valuable zeitgerber, which is the sun. Modern lifestyles, work schedules, and indoor living has altered the amount of sunlight we receive as well as how we set our schedules.

It used to be that people generally woke up at dawn, worked and spent much of their day outside or near a window, and at nighttime they read by low levels of light until retiring to bed. For better or worse, we don't follow that pattern any longer.