While the discovery of artificial light certainly has made us a more productive and efficient society, there is a dark side to light that many high achievers would do well to consider. According to the May, 2012 issue of Harvard Health Letter, the light that sets us aglow at night as we work well past "quitting time," check email, send texts, share information on social media sites, and flip through pages on e-readers puts us at risk for serious health problems, and this is especially true when it comes to types of light emitted by electronics and energy-efficient lightbulbs. According to the article, although blue wavelengths are beneficial during daylight hours because they boost our attention, reaction times, and mood, they can be quite disruptive to our health and well being at night, particularly in today's high-powered electronic age where screens rule—day and night.
The average circadian cycle is twenty-four and a quarter hours, but it is daylight that keeps our internal clocks aligned with our environment. When we upset the balance with repeated exposure to light at night, it can throw our rhythm off and wreak havoc on our health. This effect has been demonstrated through numerous experiments showing that certain types of cancer (breast and prostate) are associated with night shift work and exposure to light at night.
Although researchers are not yet certain exactly why night light exposure has such a negative impact, they believe it's at least partly related to the fact that exposure to light suppresses the secretion of melatonin, a hormone that affects circadian rhythms (some preliminary research suggests that lower melatonin levels may explain the association with cancer). In fact, one researcher, Professor Abraham Haim at the University of Haifa, believes that light at night is a carcinogenic environmental pollutant that will continue to negatively impact our health and well being until the world recognizes its harmful effects and makes important changes to how and when we use light.
Harvard researchers also have found a possible link between disruptions in circadian rhythms and diabetes and obesity. When subjects were put on a schedule which gradually shifted their circadian rhythms, their blood sugar levels increased and their levels of leptin, a hormone that causes people to feel full after a meal, decreased.
Furthermore, sleep experts have long contended that exposure to light at night interferes with sleep, and this view has found support from research. For example, a 2011 study published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM) revealed that exposure to artificial light between sunset and bedtime strongly suppresses melatonin levels, which can negatively impact physiological processes that are regulated by melatonin including sleep, thermoregulation, blood pressure, and glucose levels.
Types of Light and their Impact
According to the Harvard article, "While light of any kind can suppress the secretion of melatonin, blue light does so more powerfully." In an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness, Harvard researchers and their colleagues discovered that blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours versus 1.5 hours).
In another study out of the University of Toronto, researchers compared the melatonin levels of people exposed to bright indoor light who were wearing blue-light–blocking goggles to those exposed to regular dim light without goggles and discovered that melatonin levels in both groups were about the same, supporting the hypothesis that blue light suppresses melatonin secretion.
Haim's research has found similar results, showing that white LED light (which is blue light on the spectrum) suppresses the production of melatonin five times more than the orange-yellow light given off by traditional high-pressure sodium (HPS) bulbs and that metal halide bulbs, often used for stadium lighting, suppress melatonin at a rate more than three times higher than the HPS bulb.
According to Dr. Luis Arrondo of Foundational Healing, examples of light sources high in melatonin-suppressing blue light include:
What You Can Do
What You Can Do
1) Although glasses that block out blue light can be rather expensive, if you do a lot of work at night, it might be worth it to invest in them.
3) If you must use a night light, use dim red lights. According to the Harvard Health Letter, "Red light has the least power to shift circadian rhythm and suppress melatonin."
4) Avoid the melatonin-suppressing light sources described above, beginning two to three hours before bed.
5) Expose yourself to bright light during day time hours, which should not only improve your mood and alertness during the day, but also help you sleep at night.
6) Reconfigure lighting in your home so that it mimics fire light, which is rich in red and yellow wavelengths. Dr. Arrondo says, "This could mean shutting off the overhead lights and using floor and table lamps with orange and yellow bulbs in the evening. Of course, it also means forgoing computer and television use, especially just before bedtime. It may sound drastic, but for the person with persistent insomnia, these changes can help."
© 2012 Sherrie Bourg Carter, All Rights Reserved
Sherrie Bourg Carter is the author of High Octane Women: How Superachievers Can Avoid Burnout (Prometheus Books, 2011.