The research also highlights the significant long-term consequences for human health, including the potential dysregulation of blood sugars posed by lengthy exposure to blue light.
Given the prominence of LED lighting and the fact that LEDs emit towards the blue end of the spectrum with very little red, the researchers suggest that this may be a potential public health issue.
Mitochondria provide energy for vital cellular processes, using oxygen and glucose to produce the energy-rich nucleoside adenosine triphosphate (ATP).
Previous studies have established that long-wavelength light between approximately 650-900 nm (spanning the visible through to the near-infrared range) can increase mitochondrial production of ATP which reduces blood glucose and also improves health/lifespan in animals.
To explore the impact of 670 nm red light on blood glucose, the research team recruited 30 healthy participants, who were then randomised into two groups: 15 in the 670 nm red light group, and 15 in the placebo (no light) group.
The participants had no known metabolic conditions and were not taking medication.
They were then asked to do an oral glucose tolerance test and record their blood glucose levels every 15 minutes over the next two hours.
Participants who received red light exposure 45 minutes prior to drinking glucose exhibited a reduced peak blood glucose level and reduced total blood glucose during the two hours.
Professor Glen Jeffery is Professor of Neuroscience in the UCL Institute of Ophthalmology.
He said: “Sunlight has a balance between red and blue, but we now live in a world where blue light is dominant because although we do not see it, LED lights are dominant in blue and have almost no red in them.
“This reduces mitochondrial function and ATP production. Hence our internal environments are red-starved.
“Long-term exposure to blue light is potentially toxic without red.
“Blue light on its own impacts badly on physiology and can drive disrupted blood sugars that may in the long run contribute to diabetes and undermine health spans.
“Pre-1990, we all had incandescent lighting which was OK because it had the balance of blue and red similar to sunlight, but there is a potential health span time bomb in the change to LEDs in an ageing population.
“This can partly be corrected by spending more time in sunlight.”
