You know that your eyes are important every bit as much as your optometrist does.  Your eyes are your portal out into the world and the much of the way that you navigate your world revolves around the light that hits your eyes.

One of the great things that the body has managed to use the presence of the eye to do is create a body clock.  By using the amount of light around as a cue, humans have an in-built circadian (daily) rhythm of very close to 24 hours.  This has worked well for thousands of years – the light in the morning triggers our body’s get up and go responses and the falling light of evening results in us feeling tired.

Tablet in bedModern life however is nowhere near as dark as days previously.  Aside from the obvious bright lights of the big city, our behaviours have changed and we spend an awful lot of time in artificial light, much of which comes from computer screens, televisions and mobile devices.  Use of personal electronic equipment in the evening has massively increased in the last 5 years.

Although we all learned as small children that when mixing paint the primary colours are red, yellow and blue, the system used by screens is a little different.  Televisions and the like use the ‘additive’ system of replicating colours by using red, green and blue light.  Anybody who has gotten a little too close to their television will have seen the small red, green and blue dots that shine at different brightnesses in order to mix different colours.

The light at the blue end of the spectrum causes the biggest problem to the body’s circadian rhythm.  During the day, natural blue light levels boost concentration and mood, but too much blue light in the evening causes problems.  Because the body uses the light from the eyes to trigger chemical responses, by flooding it with light, it prevents the body from releasing a hormone called melatonin that helps to induce sleep.  A lack of melatonin therefore stops us from feeling as tired and interferes with sleep patterns and the effect is greatest when using blue light.  While we sleep, the body usually converts melatonin into serotonin, a neurotransmitter that is responsible for our feelings of wellbeing and happiness, so a lack of melatonin can inhibit serotonin creation.

It’s also long been known that people working nights for long periods are more likely to suffer more from certain types of cancer, including the most common types in women and men.  It’s also been potentially linked with certain diabetic conditions, and upon testing by slight shifting in the circadian rhythm; subjects had increased blood sugar, putting them in a pre-diabetic state.  While it’s not known how exposure to light during the night can be involved in these conditions, the most immediately noticeable effects come from blue light exposure.

As we know that blue light has the greatest effect on our circadian rhythms, there are measures that we can take.  It’s common advice to avoid bright lights shortly before bed and make sure that bedrooms are as dark as they can be.  A simple and easy solution is to avoid the use of electronic devices before bed.  There are people, however, who are naturally night owls, or may have to work late with computers.  The good news is that there is a coating that can be added to ordinary glasses which blocks blue light.  Studies have shown that wearing a coating to screen out the blue end of the spectrum prevents the exposure to blue light which in turn prevents the body from reacting negatively resulting in the same levels of melatonin as seen in people not subjected to blue lights.

The Blue-Shield coating is normally £60 extra, but until the end of April we will be doing it for the price of a normal Anti-Reflection Coating.

Image source: GSS News