The Importance of Red Light for our Health
- 2 days ago
- 3 min read
A recent article in the New Scientist flagged up the benefits of red light on the human body’s health and wellbeing and the issue that many of the LED light sources that we use inside buildings are deficient in this part of the light spectrum.
Professor Bob Fosbury at UCL has studied this phenomenon for many years. He notes the significant difference between exposure to the full spectrum of natural sunlight and the limited range of light we typically experience indoors. With modern lifestyles increasingly centred around indoor environments and artificial lighting, he described this lack of natural light exposure as a form of “21st Century Scurvy.”
Sunlight is composed of all colours of the visible spectrum from red to violet light (seen when a rainbow forms) but about 50% of it is Infrared (which humans perceive as heat) and 5% is Ultraviolet (which can cause sunburn). See this scale below to show the wavelengths of light involved:
Prof Fosbury also emphasised the importance of near-infrared (NIR) light, which is abundant in natural environments and particularly prevalent in light reflected from plants and trees. This wavelength of light may play an important role in supporting healthy mitochondrial function, which is closely linked to energy production, cellular health, blood sugar regulation and the ageing process.
Mitochondria are often described as the “powerhouses of the cell” because they are responsible for producing the energy that our cells need to function and helping with tissue repair.
Old style incandescent bulbs which produced light by heating up a metal filament, produced a continuous, smooth, full-spectrum light rich in warm red and containing at least some near infrared wavelengths. This mimics natural sunlight and the lack of flicker in the light is considered to reduce eye strain.
A standard LED light, whilst having huge efficiency and size benefits compared to previous light sources, has a light emission profile that is not the same as daylight. There is commonly a large peak in the blue region of the spectrum and a tail off into the red region. See the graphs on the middle of the following page:
and the comparison to a full daylight spectrum here:
We can see that the warmer white LEDs have more red than the cool white ones, but still a lot less than we would get from daylight.
Another issue is that the blue light peak is actively detrimental to mitochondrial function as it increases oxidative stress, lowers oxygen use and causes DNA damage which undermines cellular health.
One solution is to make as much use as possible of natural lighting in buildings. As long as solar glass has not been fitted, then this should let in some Infrared radiation as well as a good amount from the red end of the spectrum.
Another possibility would be to add Infrared lights to a building – this may work in winter when a bit of warmth is needed. Skin exposure in the morning could help mitochondrial function and also circadian rhythm.
In the longer term, a possible solution to these issues lies in tuning or reengineering LEDs or other light sources to produce a more complete light spectrum. In indoor agriculture, growers already use red enriched lights to accelerate plant growth and development. Clearly this would need to still create a comfortable ‘white’ visual environment whilst incorporating the beneficial red end of the light spectrum.
For home use it is still perfectly legal to buy and use old incandescent bulbs. This may be of benefit in the evenings to prepare the body for sleep by removing the stimulating excess blue light that LEDs can produce. The full spectrum light is more beneficial for the human circadian rhythm by better allowing the hormone melatonin to prepare the body for sleep. There is, of course, the trade off with higher running costs and also the need to check modern light fittings for the maximum wattage allowed since incandescent bulbs can get very hot.
