Circadian Rhythms – Our Body Clock

Our Internal Body Clock

MindSpa can help with two of the major causes of sleep disruption, high stress levels and lack of adequate light. When you use MindSpa as we suggest, we guarantee you will experience a marked improvement in your quality of sleep.

Light is a powerful regulator of the human circadian system, our biological clock, the “body clock.” Circadian rhythms are the internal 24 hour clock controlling physiological changes that occur with the natural light-dark cycle of the day.

The SCN or suprachiasmatic nucleus acts as the central processing system for our biological clock. It is located in a part of the brain, the hypothalamus, just above the point where the optic nerves cross. Light reaches photoreceptors in the back of the eye, the retina, generating signals that travel along the optic nerve to several areas of the brain including the SCN, which is a non-visual part of the brain. In addition to sleep/wake cycle regulation, the SCN also plays a primary role in hormone secretion, body temperature and blood pressure regulation, among other daily functions.

In the presence of light, or the lack thereof, signals from the SCN travel to various parts of the brain, including the pineal gland. Among its responsibilities, the pineal gland controls production of the hormone melatonin, the sleep hormone.

Melatonin levels normally increase in the absence of light. Exposure to specific light frequencies suppresses melatonin production for several hours. Melatonin makes us feel drowsy and plays a role in mood change. However, this only begins to describe the critical role Melatonin plays in regulating body function. We suggest further independent reading on its role. Here is one recommended link to the University of Maryland Medical Center on the role of melatonin

The retina contains three types of specialized photoreceptors that respond to the visible light spectrum. Visible light ranges from approximately 370 nm to 730 nm, indigo to red. These photoreceptors consist of the rods, cones and the recently discovered light/dark receptors also referred to as the melanopsin photo receptor cells.


The rods are the most numerous photoreceptors, and the most sensitive to light, but are not sensitive to color. The retina contains approximately 110 – 125,000,000 rods. They are primarily responsible for dim light vision. The rods peak in the blue range and have almost no response to red light. Known as the scotopic photoreceptor system, the peak wavelength sensitivity is 507 nm, the green/blue-green color range.

The cones are color sensitive and divided primarily into red and green cones with a small percentage of blue cones. There are approximately 6.5 million cones in the retina divided into approximately 64% red sensitive cones, 32% green cones, and 2% blue cones. The blue cones are more sensitive to light than the red or green cones. The cones are responsible for high resolution vision known as photopic photoreceptor system. The cones have a peak wavelength sensitivity of 555 nm, the green spectrum.

The Melatonin Action Spectrum

This is where it becomes interesting… In 1998 scientists discovered a specialized set of cells in the retina that respond specifically to short wavelength blue light in the 446-483 nanometer (nm) range. This is also the wavelength of the clear, blue sky. Called the action spectrum, this blue light wavelength band plays a major role in aligning and resetting the body clock through the control of release of the sleep hormone, melatonin.

The melanopsin receptors are independent of the classic rod and cone photoreceptors used for vision, and are not part of the visual system. They are active even with eyes closed and while asleep. It is theorized that blue sky exposure is how these ganglion cell photoreceptors evolved their specialized purpose.

These photoreceptors regulate circadian rhythms primarily via melatonin secretion. When exposed to this specific band, melatonin production is suppressed for several hours. The MindSpa CalmBlue glasses are tuned within a few nanometers of the peak frequency range making them very effective for resetting the body clock. Here is a very helpful National Institute of Health article on these photoreceptors operate and the unique human health effects of blue light.

Stress & Anxiety

Many sleep issues are stress related. We tend to enter into what is known as mental loops. This is where, especially in the quiet of the night, we maintain an inner dialog, going over and over problems generally related to money, work or relationships. We are all familiar with this. It leaves us anxious and agitated making quality sleep difficult to attain.

Normal beta activity is associated with regular, active thinking processes while awake. Mental loops will cause our mind to remain in the high “beta” activity state. During the night we go through approximately a 90 minute sleep cycle. It is during the lighter sleep phase when beta activity can spike causing us to wake up. So instead of dreaming, we are so anxious it knocks us right out of the sleep cycle.

Stress can cause our mind to move into a combination of fast, high intensity beta brainwaves. In this state, we are not so much solving problems as just thinking about them. MindSpa’s relaxation programs help to disrupt these mental loops by generating natural alpha state relaxation rhythms. With regular use, the mind will naturally attune to these alpha waves quieting and slowing down our internal dialog. When we are relaxed, we can fall asleep and stay asleep more easily. The quality of your sleep will improve.

Light Related Issues

Imbalances in circadian rhythms are another major cause of sleep disruption. We are light-regulated beings. A lack of proper daily light will disrupt our internal body clock. MindSpa can assist by providing the correct does of blue light for resetting rhythms when natural light in sufficient quantities is not available.

Light plays a remarkable role in our health and general well being. Light is as important a supplement as any vitamin, mineral, or anti-oxidant. Proper exposure to beneficial wavelengths of light is absolutely necessary for our overall health and balance.

As we have modernized, we have effectively cut ourselves off from natural light. We wear sunglasses to the point of cutting off beneficial light wavelengths from entering the eye. We have moved from the natural environment into buildings, which are like modern caves depriving ourselves of the benefits of natural light.

Stress and a lack of beneficial light are among the root causes of a virtual epidemic of sleep disorders throughout the developed world. Quoting from Forbes, April 13, 2006; “According to the National Institutes of Health, sleeplessness creates $16 billion in annual health care expenses and $50 billion in lost productivity.

Scientists are finding that chronically reduced or disrupted sleep may increase the risk of obesity, diabetes and cardiovascular disease. “We know from all the research that sleep is just as important to overall health as exercise and diet,” says Carl Hunt, special assistant to the director of the U.S. Heart, Lung & Blood Institute at the NIH.”

Circadian Rhythm Disorders

Circadian rhythm disorders are typically related to sudden and/or extreme changes in the relationship between exposure to environmental light and activity. For example, circadian rhythm disorders are known to be associated with change in geographical location (jet lag), aging, and night activity (night time shift workers).

Another common type of circadian rhythm disorder is seasonal affective disorder (SAD), which is characterized by symptoms such as lethargy and depression during the winter seasons when the duration of daylight is reduced. Due to decreased light exposure melatonin production continues during the waking hours.

Symptoms much like jet lag are common in people who work nights or who perform shift work. Because shift work schedules are at odds with powerful sleep-regulating cues like sunlight, they often become uncontrollably drowsy during work, and they may suffer insomnia or other problems when they try to sleep. Here is another National Institute of Health article on winter seasonal affective disorder (SAD).

Shift workers have an increased risk of heart problems, digestive disturbances, and emotional and mental problems, all of which may be related to their sleeping problems. The number and severity of workplace accidents also tend to increase during the night shift. Recent evidence suggests it may be possible to reduce shift-related fatigue by exposure to specific frequencies of blue light in the workplace, minimizing shift changes, and taking scheduled naps.

Sunlight also causes other changes in the body, such as increases in serotonin production. Serotonin neurotransmitter production increases when a person is exposed to sunlight. Low levels of serotonin are associated with depression and mood swings. Along with using MindSpa, it is important to get as much light as possible every day for health, balance and general well-being. This becomes even more necessary in the winter when light levels are low.

Using our CalmBlue™ LED Glasses

For general well being and balance use one of the relaxation sessions each morning shortly after waking up for a minimum of a one-half hour, though 45 to 60 minutes is preferred. Time of year and location play an important role. If you are receiving low exposure to natural light use more often to maintain circadian balance.

For general sleep-related issues such as going to sleep too early and waking up early, use the blue led glasses late afternoon or early evening. This is known as an advanced phase response, meaning going to sleep earlier than usual. You are using blue light tuned to the action spectrum to phase advance your internal clock. This will help you to readjust your sleep patterns to a more normal hour. While some customers report excellent results at night, we generally do not suggest use close to bedtime as this may be too stimulating and cause trouble falling asleep or possibly cause sleep disruption during the night. For the majority, use daily for 45 – 60 minutes a minimum of two to three hours before retiring to bed.

If you are falling asleep too late and/or waking up late, known as delayed sleep phase response, use daily in the early morning and try to get plenty of unfiltered morning sunlight (avoid sunglasses or tinted windows as found in autos and commercial buildings). You can actually put the blue led glasses on early in the morning and go back asleep as the melanopsin photoreceptors are still active.

Long term changes require a use every day for a minimum of 45 minutes to 1 hour in the early morning. Continue use for at least one month and preferably three to four months of regular daily dosages to experience long term benefit. We always recommend consulting a medical professional before beginning any long term program.

For common circadian related disorders such as seasonal affective disorder also called the winter blues, use early in the morning or upon awakening for a minimum of 45 – 60 minutes every day during the winter months. As mentioned, the melanopsin photoreceptors are active while asleep so you could put on the glasses after five in the morning, go back to sleep and still receive full benefit.

Note: During mid-day our sensitivity to blue light is essentially shut off. Blue led glasses have no or very limited effect during most daylight hours starting from mid-morning to late afternoon. At these times we suggest using the white led glasses with your MindSpa for maximum effect.

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