We live in a technologically advanced age where the presence of artificial light and devices like smartphones and laptops means that we are sleeping less than any other previous generation. The sun no longer dictates our schedules and we are now free to work or socialise even in the dead of the night. Unfortunately, most of these devices emit blue light which is now raising a lot of concerns as a potential public health risk. A recent study has even shown a direct correlation between blue light and increased risk of some types of cancer. But before we get there, here’s what you need to know about blue light.
Blue Light Spectrum Diagram
How do LED lights produce blue light?
The visible light spectrum is composed of various shades of red, yellow, green and blue light rays that combine to form white light. The colours of the spectrum differ considerably in their wavelengths and the amount of energy they contain. On one end of the spectrum, red light has the longest wavelength and therefore least amount of energy while blue light has the shortest wavelength and contains the highest amount of energy. Furthermore, blue light on its own makes up a third of all visible light. These facts are what make blue light the most important and widely studied component of the light spectrum.
Due to its high energy content, blue light is able to easily penetrate into the deeper tissues of the eye, a fact that allows this light to directly damage the retina in high intensities. Incidentally, exposure to blue light does have some merits, especially during the day since it keeps you alert and boosts your memory and cognitive function. It’s also the part of light that allows you to see with the highest visual acuity. The problem comes in when you’re exposed to blue light at night. Blue light is able to stimulate photosensitive receptors in the eye that signal your body to suppress the secretion of melatonin, a sleep hormone. Reduced melatonin at night causes insomnia and disrupts your circadian rhythm.
The study pointing to LED lights and cancer
In April 2018, a study performed by an international team led by the Barcelona Institute for Global Health was published in the Environmental Health Perspectives. The results clearly showed a link between blue light exposure at night and a higher risk of developing breast and prostate cancer. The researchers compiled medical and epidemiological data of more than 4000 people between 20 and 85 years old from 11 regions in Spain. Exposure to artificial light indoors was determined through personal questionnaires while exposure outdoors was measured in Madrid and Barcelona using images taken from astronauts aboard the International Space Station. The researchers then compared previous exposure to artificial light at night between approximately 2000 breast or cancer patients and about 2000 controls based in Madrid and Barcelona.
The results obtained clearly showed that participants who were exposed to a higher levels of outdoor blue light at night had a 1.5 and 2-fold higher risk of developing breast and prostate cancer respectively. Exposure to indoor artificial light also showed marked effects especially regarding the risk for developing prostate cancer. Men who slept in ‘quite illuminated’ bedrooms reported a 2.8-fold higher risk of developing prostate cancer than those who reported sleeping in total darkness.
A unique thing about the study was that it was able to specifically look at the intensity of blue light. Previous studies that used satellites only assessed the overall intensity of artificial light in large cities at night. “In this study, we focused on the satellite images because other satellites cannot see the colours but astronauts aboard the space station can,” said Dr Alejandro Sánchez de Miguel, a researcher from the University of Exeter and a lead author on the study. “And so this is the first study to put an experimental value on the correlation between blue light and the general population with the risk of breast cancer and prostate cancer.
According to the study, only outdoor artificial light that was high in blue light showed a direct correlation with increased risk of cancer. Other kinds of outdoor artificial light like those rich in the red and green components of the visible light spectrum showed no similar effect. This is an important discovery that clearly proves that only blue light is responsible for cancer rather than the general brightness of outdoor artificial lighting. It’s certainly a worrying prospect considering the new trend of major cities switching to LED street lights that emit a lot of blue light.
So what is it about blue light that increases the risk of breast and prostate cancer? It all boils down to the effect on melatonin and the circadian rhythm. As previously stated, blue light at night suppresses the production of melatonin which ultimately disrupts your biological clock. Other than controlling your sleep-wake cycle, your biological clock maintains the efficient working and synchronisation of all of your physiological functions; that includes hormone production. Interfering with the circadian rhythm therefore disturbs the hormone levels in your body which is a significant risk factor for hormone-sensitive cancers like breast and prostate cancer. Melatonin on its own also has anti-oxidant and anti-inflammatory properties which help suppress the development of cancers when in adequate levels. The suppressive action of blue light on melatonin thus abolishes these effects.
What can you do about blue light from LED’s to prevent cancer?
Even though the study only focuses on blue light emitted by outdoor artificial light sources, blue light is also emitted by smartphones and laptops. The researchers warn that the same mechanism may be affecting the devices and bulbs at home because ultimately, the physiology is the same. It’s therefore prudent to take appropriate measures to reduce your exposure to blue light at night from your devices and artificial lighting. To get you started, visit our product page for LED lighting with special anti blue light properties.