The Circadian Rhythm and Sleep

When you find yourself feeling the effects of jet lag, or when you feel tired after working a rotating shift during the week, what actually is happening is that your body's circadian rhythm has been offended. The word "circadian" comes from the Latin words circa diem. This phrase, when translated into English, means about a day. In our conversations or literature, we can split hairs,, but, as far as our body is concerned, one day refers to a 24-hour period.

We most commonly hear about circadian rhythm when discussing humans and their sleep patterns. What is often overlooked is that it also has a direct influence on our blood pressure, our body temperature, and our body's production of hormones.

Taken together, these internal changes let your body know when it is time to sleep, and to wake, and how your mood will tend to be at any given time.

You have to remember that rhythm is a very big part of almost everything in nature.

For example, we know that the Earth completes a rotation every 24-hours.

That's rhythm!

We are acutely aware that, year after year, the seasons change...from winter to spring to summer to autumn and then back again to winter.

Again, that's rhythm.

Natural not only to humans, circadian rhythm plays a significant role in the lives of animals as well. Perhaps one of the most notable examples of an annual natural rhythm among animals is the migration of countless species of birds every year.

The return of the swallows to Capistrano every year, and the southward flight of geese in the Fall, are related to this natural rhythm.

When we talk about the sleep-wake cycle, there are two primary environmental forces at work. These are light and temperature. However, circadian rhythm can also be affected by other stimuli such as the sound of your alarm clock and what and when you have eaten, and, in women, their menstrual cycles.

An Internal Clock

Within all humans and animals, circadian rhythm is under the influence of an 'internal clock' located in the part of brain called the hypothalamus. More specifically, two rather large clusters of neurons situated on either side of the brain, which are called the Suprachiasmatic nuclei or SCN are viewed as the body's master clock. The SCN also work with other genes to help the body keep track of time.

The stimulation, which results in the release of different chemicals, hormones and neurotransmitters is how the body knows when it is time to fall asleep and to wake up, when it's time to eat and when it's time to have intercourse and more.

When it comes to sleep, the following is a bare bones overview of how the circadian rhythm works.

At the first signs of daylight, your body begins to produce hormones and neurotransmitters including serotonin and cortisol. These help your body transition into an awakened mode by increasing your body temperature and blood pressure.

Likewise, as daylight fades, the body begins to release melatonin, the main signal that tells the body to begin lowering blood pressure and to prepare itself for sleep.

In fact, one tip for good sleep is to expose yourself to a healthy dose of daylight as soon as possible after rising. This sets your body's internal clock and actually can help your body prepare to drop off to sleep naturally several hours later.

When the body's circadian rhythm is in balance, it dictates the proper timing and release of these important chemicals, hormones and neurotransmitters. However, when the body's circadian rhythm is not working properly, this timing and release is knocked out of balance. A prolonged imbalance can and often does lead to the development of a number of sleep disorders and emotional disturbances. It would seem, you see, that being healthy and happy is a lot about keeping your circadian rhythm in good working order.