We’re instinctively drawn to natural light. But our need for sunlight goes beyond our ability to see or feel its effect on our skin.
Life on earth could not be possible without the sun and the light it produces.
From the beginning of time, the natural cycle of the sun has set the rhythm of life.
Like many animals, humans are naturally programmed to be awake and active during the day, when the sun is up; and to sleep at night, when the sun is down.
But as we spend more and more of our time indoors, our daily access to natural light has become limited.
Nowadays, our primary sources of light are artificial, but not all light is equal and electric light can have downsides when it comes to our health and wellbeing.
In the human eye, light is detected by specialised cells that send signals to the region of the brain responsible for vision. But these cells also send signals to the region of the brain that controls our biological clocks and circadian rhythms.
The human body is naturally programmed to function on a 24-hour internal clock that matches the solar day.
Known as the circadian rhythm, this clock is synchronised by light and controls many aspects of our physiology, metabolism, and behavior, including our sleep-wake cycle.
Melatonin is a hormone produced by the brain that plays an important role in the regulation of our sleep wake-cycle.
Melatonin production naturally starts to increase in the evening, peaks in the middle of the night; and rapidly declines in the morning, allowing us to wake-up.
Exposure to blue light or bright light before bedtime can lead to melatonin suppression, which can delay sleep onset and shorten sleep duration. Inversely, exposure to blue-enriched bright white light in the morning can have an energising effect.
Light sources can vary in colour, from warm, orange light to cool, blue light. Light can also vary in intensity, from dim to bright. Lights of different colours and intensities result in different responses from the brain.
Exposure to electric lights can disrupt our natural circadian rhythms, which can directly affect our health and wellbeing.