While the article states exposure to artificial light at night can throw the body’s circadian rhythm out of whack, disrupting sleep and possibly contributing to health issues such as heart disease, diabetes, several types of cancer and obesity, it also indicates that exposure to blue wavelength light at night may be the most disruptive. Blue wavelength light is beneficial during daylight hours, offering benefits such as boosting mood, increasing attention and improving reaction times. However, after the sun naturally goes down, these same blue wavelengths have the most adverse affect on sleep.
Although studies haven’t yet confirmed why exposure to light at night, such as for shift workers, is so bad for health, it is thought that it may be due to the suppression of melatonin secretion that occurs with exposure to light at night. Melatonin is important in regulating circadian rhythm and a lack of sleep may be linked to major health risks. Studies by researchers at Harvard and the University of Toronto have shown that blue light effects melatonin secretion more significantly than other wavelength colors.
The article suggests that while the amount of blue wavelength light emitted by fluorescent and energy-efficient LED lighting can’t naturally change, the inside of lightbulbs can be coated to produce a warmer light with less blue wavelengths. Although not mentioned in the article, variable color Walalights will adjust to emit warmer light after dark, reducing some of the negative effects that are experienced due to exposure to blue light at night.
The entire article from the Harvard Health Letter, titled “Blue Light Has A Dark Side”, can be viewed below…