Correlated Color Temperature (CCT) measures the hue of light in Kelvins. Natural light varies in CCT throughout the day, influencing circadian rhythms. Warm light (around 2700K), seen at sunrise and sunset, promotes melatonin release, aiding rest. Cool light (above 5000K), typical at noon, suppresses melatonin and boosts cortisol, enhancing alertness and activity.
How can light affect our circadian rhythms?
Just like food and water, light is a nutrient for the human body. For humans, light reaching the back of our eyes is the primary external cue that synchronizes the body’s internal biological clock and thus our circadian rhythms to the solar day, essentially telling our bodies to do the right thing at the right time .
NATURAL LIGHT CHARACTERISTICS
Dark-light cycle
The dark-light cycle is a 24-hour pattern of daylight and darkness that has shaped human biology over thousands of years. This cycle influences circadian rhythms, the internal 24-hour clock that regulates physical, mental, and behavioral processes. Light plays a key role by signaling the brain, which controls physiological functions like hormone levels and the sleep-wake cycle. Exposure to natural light aligns these rhythms, supporting overall health and adaptation to the environment.
Color Temperature
Light Intensity
Light intensity changes throughout the day, from dim at sunrise to bright at noon and dim again at sunset, influencing hormones. Measured in lux, intensity ranges from 10,000 lux on sunny days to 0.001 lux under starlight. Light below 30 lux promotes melatonin release for restful sleep, while light above 30 lux suppresses melatonin to keep us alert and active.
ARTIFICIAL LIGHT CHARACTERISTICS
Dark-light cycle
Due to our modern lifestyle, we spend most of our time indoors, under artificial light. Compared with natural light, artifical light is not dynamic and the lack of dark-light cycles will alter our internal clock and circadian rhythms.
Color Temperature
With artificial lighting, light color temperature (CCT) is fixed from wake-up to go-to-sleep. It is generally a cold light (above 5000K) all day long.
Light Intensity
Artificial indoor light typically has a fixed intensity of 300-500 lux, much lower than natural light, which reaches 10,000 lux or more on sunny days and 1.000-5.000 lux on cloudy days. In addition, this intensity at night is too high, far from the darkness our body needs.
Artificial lighting alters light intensity, spectrum and dark-light cycles, exposing us to less light by day and too much at night. This disrupts natural circadian rhythms, contributing to issues like sleep disorders, apathy and depression.
90%
Of our time spent indoor
40%
Of people suffer of sleep disorder
70%
Of people suffer of depression