The human body like all living things has an inner time clock, which is hormonally linked to daylight. And the Hormone of sleep, Melatonin is most sensitive to the blue spectrum contained in daylight. Exposure to this component of light switches off Melatonin production and this delays sleep onset.
However, it’s thought that a shift in this time clock not only controls our wakefulness but also all the individual clocks that dictate the function of the organs in the body – and these are far more difficult to monitor than sleep. In other words, things that affect our sleep clock, such as blue-light exposure, have a much more serious consequence than originally thought. Health professionals are beginning to suspect that long term disruption in our internal time clock(s) may have an impact on many of our chronic ailments; from depression to obesity and even cancer.
But first let’s look at how this all works: what exactly is Daylight?
We only perceive a tiny portion of what the sun sends out to us, called the visual spectrum. We see everything between the Ultraviolet UV and the Infra-Red (IR) spectrum. The thing about daylight is that it constantly changes, depending on the time of day and location on this earth.
In the morning there is a very high proportion of blue light in the atmosphere as the sun rises and this very quickly suppresses melatonin levels (so we become more alert). The amount of blue light peaks around midday and then begins to fall as the sun begins to descend.
At sunset there’s virtually no blue light present in daylight – it’s all at the Infra-red end of the spectrum. This lack of the blue component allows melatonin production to be switched back on so our bodies are signalled to rest.
This brilliant design by nature is absolutely perfect. We’ve evolved so that our hormonal inner clock is completely aligned with the composition of daylight throughout the day. We were once completely aligned with nature and our planet….and then mankind decided to create stuff!
That means, in this modern age, we are getting bombarded with much more blue-rich light than EVER before. Our poor brains just don’t know what to do anymore. Instead of a steady decline into blue light to allow us to begin to secrete melatonin at the end of the day.
As a result we sleep less, feel less refreshed. That leads to elevated stress hormones. We feel tired, run down and over alert: our immune system becomes compromised. We become out of balance and develop dis-ease. It’s a vicious cycle that can become hard to break and really impacts on our health.
So what can we do? Well help is at hand. Recent developments in technology allow us to set a “night time” mode on your phone. This reduces the amount of blue light emitted and turns the brightness down as you approach bedtime.
The latest LED lamps have “warm-dim/ tuneable technology” whereby an amber LED kicks in as it dims down to produce a warmer light. Recent developments have produced "tuneable white" LEDs whereby you can set the colour temperature of the white light to more closely mimic that of natural daylight.