How Should Light Really Be Measured?

Back in May, ANSES, which is the French Government’s agency for food, environmental, and occupational health and safety, released findings on a study they conduct over the past nine years. The study was on the impact of LED lighting on people, animals, and plants.

The study was commissioned due to the planned withdrawal of incandescent lamps and conventional halogen lamps, which has led to a strong development of LED lighting products. Therefore, increasing human exposure. When publishing its first opinion on the health effects related to LED technology, back in 2010, ANSES drew attention to the toxic effects to the retina from blue light exposure. Now, the potential health impact from blue light exposure is better documented.

To further their research, ANSES commissioned an expert working group made up of experts in the field of physics, metrology optical radiation, vision, ophthalmology, chronobiology, biology, environment and regulation in the field of lighting. Scientific evidence conducted by this group of experts confirms the “photoxic effects” of short-term exposure to high-intensity blue light, as well as increased risk of age-related macular degeneration, after chronic exposure to low intensity sources. Age-related macular degeneration, is a leading cause of vision loss of people over 50.

As noted in ANSES’ report, the human health risks associated with exposure to LED light are mainly due to the spectral composition and the temporal modulation of the second light. A sampling of further findings on the impact of blue light on human health include:

  1. The impact of blue light exposure to one’s health, including photoxicity and disruption of circadian rhythms are very dependent on the age of the exposed person. Children are born with a clear lens, and cannot filter blue light as well as someone older. People over 60 have a greater ability to filter blue light.

  2. The effective synchronization of the central circadian clock and therefore the biological functions that depend on it, including the pace of sleep / awake time, requires high light intensity during the day and total darkness at night. Current lifestyle trends, tend to deregulate the natural daily rhythm of light vs. dark. Many studies have shown that exposure to high intensity blue light from artificial light sources delay or inhibit melatonin secretion. Values of 10-40 lux or below, which is a very low level, that is often exceeded in household lighting, is sufficient to observe an effect on one’s circadian clock.

  3. Disruption of the circadian rhythm, as mentioned in number 2 above, leads to other disturbances such as the quantity and quality of sleep, metabolic disorders, increased risk of cancer, cardiovascular diseases, and effects on mental health.

  4. We mentioned the possible negative impact of blue light to the retina, but what about our skin? According to ANSES, blue light may have harmful effects to our skin, accelerating the aging process and delaying the healing process. However, based on our population’s current exposure to blue light, the risk of developing skin diseases linked to exposure to blue light from LEDs, is low. Although risk is currently low, it is a study we are going to continue to follow.

Some of the noteworthy conclusions from the study include the following:

Develop actions and information on:

  1. Limiting exposure to rich blue lights, from LEDs or other technologies, favoring the use of warm color lighting (color temperature below 3000K), before bed and during the night hours.

  2. The importance of increasing the light contrast between day and night, by increasing natural light exposure during the day, and limiting artificial light exposure before bedtime and during the night hours.

  3. The phototoxic effect of light associated with exposure to certain LED lighting.

  4. The adverse health effects associated with exposure to LED.

Research related recommendations:

  1. Improve the quantitative assessment of the impact of a general shift to LED technology on human health and the environment.

  2. Continue and intensify research on the disruption of circadian rhythms by light and the resulting effects on alertness, sleep, mood, well-being, cognition, and health.

  3. Increase knowledge of LEDs temporal modulation on visual, biological and health effects.

While the impact of this study is eye opening, a question still remains “how should light be measured moving forward?” We have long thought innovation in lighting technology, known as LED, was progressive. Now we have to ask ourselves if that’s true. We used to base the health of food and drinks off of their calorie and fat content. We are now beginning to understand, that calories and fat are a small piece of what makes a food or drink healthy, or not. Where was the food sourced, are the ingredients organic, is it made up of healthy fats, what’s the sodium content, are just a few of the questions we now ask ourselves, to determine if a food or drink is indeed healthy.

We may not consume light the exact same way we consume food. However, we do consume light. As stated by the Kellog Eye Center “Light passes through the front of the eye (cornea) to the lens. The cornea and the lens help to focus the light rays onto the back of the eye (retina). The cells in the retina absorb and convert the light to electrochemical impulses which are transferred along the optic nerve and then to the brain.”

With all of these new studies on the negative impact that artificial light has on human health, maybe it’s time we started asking more questions about the health of the light we are consuming every day.


Effects on Human Health & the Environment LEDs: ANSES. April 5, 2019.

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