Your circadian rhythm is responsible for the mental, physical and behavioral changes that you experience every day. According to the National Institutes of Health, circadian rhythms are the body’s response to light and darkness. While circadian rhythms are not the same thing as an individual’s biological clock, biological clocks drive circadian rhythms. By knowing what circadian rhythms influence, you’ll have a greater understanding of how light therapy can keep you on-track during the dark winter months.



In addition to controlling sleep-wake cycles, circadian rhythms affect or contribute to:

  • Hormone production and release
  • Body temperature
  • Moods
  • Heart rate
  • Blood pressure
  • Mental health
  • Appetite
  • The growth and spread of some forms of cancer
  • Jet lag
  • DNA repair
  • Metabolism


The body has several biological clocks in the molecules that control circadian rhythms throughout the body’s cells. A master clock, your brain, controls the biological clocks via the suprachiasmatic nucleus, or SCN, a group of nerve cells in the hypothalamus.


The SCN receives signals from the eyes, based on the type and amount of light to which they are exposed. When the light is bright and has white and blue wavelengths, like natural light during the day, the SCN tells the brain to produce serotonin, which keeps you awake and gives you energy. When the eyes sense darkness, the brain converts serotonin into melatonin, which helps you fall asleep.


In addition to biological clocks, genetic factors and proteins in the body affect circadian rhythms. A 2011 LiveScience article reports that researchers at the University of California, Irvine, discovered in 2006 that the proteins CLOCK and SIRT1 largely influence circadian rhythms in humans other organisms. Upsetting the balance between the two proteins leads to increased hunger and sleep disruptions. Prolonged imbalances contribute to obesity.


In addition to the brain, different organs in the body have their own circadian rhythms. These organs produce enzymes, hormones and other molecules at different times of the day. These organs take cues from the brain. A metabolic disorder, such as diabetes, occurs when the brain and organs are out of sync. In the case of insulin resistance, the pancreas, liver and brain aren’t coordinated, causing too much or too little insulin production.



One of the more notable circadian rhythm disruptions that many people have experienced is jet lag. Another is the seasonal variation in natural light when the days are shorter in the fall and winter. When this occurs, it is common for people in affected areas to feel more lethargic or even crave high-carbohydrate foods. A percentage of the population also experiences seasonal affective disorder, or SAD.


To combat the effects of the seasonal changes in daylight, simple light therapy techniques include allowing more natural light to enter a room, sitting next to a window more often and regularly exercising outside, particularly in the mornings.


Exposure to natural light puts you in direct contact with the blue and white wavelengths that stimulate a sense of wakefulness. If you’re in an area where the days are notoriously short, you can receive the same benefits with light therapy products, such as those offered by Nature Bright. Numerous studies show that the wavelengths emitted by therapy lights work just as well as natural light. The trick is to use them at the right times of day. Aim for at least three times a day in the morning and afternoon. In the evening and night, avoid the use of bright therapy lights because this is the period when your brain prepares for sleep.


From supporting plant life to creating beautiful sunsets at night to regulating various functions in the body, light has a major role in how the world works. Thanks to scientific advances, you can use light therapy throughout the year to naturally regulate circadian rhythms and improve or maintain your overall well-being.