Up until recent times, it was believed that light was only needed for seeing. However, in 2001, American scientist, Brainard, discovered a circadian photoreceptor in the retina of the eye, that receives a specific quality and quantity of light, which sets the biological clock.
He discovered that light not only provides us with the ability to see, but that light enters the eye via the ‘fourth pathway’, which has a vital non-visual or biological effect on the human body. His studies show that a certain quantity and quality of light stimulates the biological clock, also known as the circadian rhythm, which regulates hormone levels, particularly melatonin and cortisone in the body.
Bio-dynamic lighting is a technical method of achieving the biological effects of daylight in an artificial lighting environment. This method of lighting mimics the cycle of natural daylight, changing colour temperature and intensity throughout the day. In very simple terms, it is brighter and whiter in the morning and dimmer and warmer in the evening – but there is far more to it than simply changing the colour and intensity of the light.
Bio-dynamic or circadian lighting is most often used in a healthcare or office environment, although it has started to become popular for general residential lighting as well. Our biological clocks are genetically preset to work with the 24-hour cycle, but we need to re-synchronise daily through exposure to daylight, or to artificial light designed to replicate daylight. This synchronisation helps regulate the levels of the hormones melatonin, cortisol and serotonin, all crucial elements in keeping our biological systems in balance. If exposure to daylight is missing, sleep disorders, chronic fatigue and/or depression can follow.
Bio-dynamic lighting should be considered for any environment in which people spend a significant amount of time without getting regular and prolonged exposure to daylight. Many offices and healthcare facilities fall into this category, as well as all types of buildings in countries that experience extended periods of darkness during winter such as those in the extreme northern latitudes.
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