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The influence of light on the human diurnal rhythm


Human Centric Lighting (HCL), or human-centric lighting, is an approach that takes into account the impact of light on the human biological diurnal rhythm. Understanding how different colours of light affect our functioning both during the day and at night is a key element of health and overall productivity.

The diurnal rhythm and light

The diurnal rhythm, also known as our internal biological clock, regulates many of our vital functions such as sleep, metabolism and hormonal balance. Lighting in our environment plays a key role in synchronising this clock with the external environment. The human biological clock is a set of mechanisms located in the suprachiasmatic nucleus of the hypothalamus of the brain, which is the regulator of the body's diurnal cycle. Its activity is mainly modulated by light signals reaching the retina, which stimulates or inhibits the production of melatonin, a hormone crucial to the regulation of sleep and wakefulness.

Effect of light colour on sleep

The colour of light has a significant effect on the quality of our sleep by regulating our biological clock. Light with a blue hue, emitted by digital screens, effectively inhibits the production of melatonin, which can lead to disturbances in the diurnal rhythm. In contrast, light with warm colours, such as red or yellow, interferes less with melatonin production, which promotes relaxation and prepares us for sleep.

Exposure to natural sunlight in the morning hours stimulates the production of cortisol, a hormone necessary to stimulate and increase energy to start the day. This is crucial for the proper regulation of our biological clock, affecting overall activity and productivity throughout the day.

Appropriate indoor lighting

Matching lighting to our diurnal rhythm and the nature of our activities is a key factor for our productivity and health. In areas intended for rest and relaxation, it is recommended to use lighting with warm colours, such as shades of orange or red. These tones promote relaxation, reduce stress and improve mood, which is particularly important for effective rest.

Workplaces, on the other hand, prefer lighting with neutral or cool colours, which promote concentration and increase alertness. Colours such as white or blue can help to maintain high energy levels and focus, which is vital when performing tasks that require attention and precision.

The importance of mindful use of light

Understanding the impact of different colours of light on the diurnal rhythm is fundamental to optimising health and bodily function. The conscious use of appropriate lighting, both at home and in the workplace, can significantly improve sleep quality, mood and overall performance. The practice of using Human Centric Lighting can be instrumental in promoting a healthy lifestyle and increasing efficiency, both personally and professionally.