It seems so self-evident that sunlight is vital to life that it almost doesn’t need to be said. But what does light do to the body apart from enabling us to see things more clearly?
It’s clear that the importance of light isn’t just about enabling us to see. Vision is but one of the many ways that our body and brain interact with light.
Light streams down on our skin and head and does many useful things to and for us. For example:
- too little sunlight as a child leads to abnormal bone development and permanent disability as an adult. We need regular doses of sunlight to grow to be strong and healthy adults.
- being in sunlight speeds the recovery of newborn babies with jaundice. When the jaundice has cleared, baby can go home.
- putting your head in sunlight makes your brain instantly sit up and take notice. Yes, really!
Imagine yourself sitting in a cave, at peace with the world in a gentle vague way. Then imagine yourself stepping out of the cave one sunny morning. Sunlight hits your head, then the red and near infrared wavelengths penetrate through your skull and land directly onto your brain cells, immediately boosting the mitochondrial batteries. Whammo – your brain cells and brain networks are galvanised. In an instant, your brain has snapped from fuzzy to full attention. Your cognitive function network is now maximally engaged, your alertness levels have been dialled up as far as possible and you scan your surroundings, ready to deal with opportunity and/or danger.
Having such a dramatic response to sunlight is pretty useful, and it would have protected our forbears from all sorts of lurking dangers. We humans are still programmed to have this response to sunlight. We may not be so aware of its value in this civilised world, but our body and brain continue to respond in this way.
This article is less than two pages long, but it presents so many ideas. There is yet another fascinating thing to tell you in a future post. (Four posts from one research paper is a blog record.)