Light plays a key role in regulating our circadian rhythm, sleep, and overall well-being. One of the most interesting discoveries in the field of chronobiology is the melanopic light effect - the ability of light to influence melatonin levels, the sleep hormone, and to regulate our daily activity.
What is the Melanopic Light Effect?
The melanopic light effect refers to the influence of light on melanopsin - a photosensitive pigment in the eye that plays a key role in regulating the circadian rhythm (the body's internal clock).
Melanopsin is located in special photoreceptor cells in the retina that are different from those responsible for vision. These cells primarily respond to blue light with a wavelength of around 480 nm.
How Melanopsin Affects the Body
When light stimulates melanopsin, it sends signals to the brain that affect:
- Secretion of melatonin - the hormone that promotes sleep.
- Levels of alertness and concentration during the day.
- Regulation of the circadian rhythm - the body's 24-hour biological cycle.
Influence of Light on Melatonin:
Morning: Light → Stimulates melanopsin → Decreases melatonin → Increases alertness
Evening: Darkness → Decreases melanopsin stimulation → Increases melatonin → Preparation for sleep
Color Temperature and Melanopic Effect:
Cool light (5000K-6500K): Strongly stimulates melanopsin → Suitable for morning and daytime
Warm light (2700K-3000K): Weakly stimulates melanopsin → Suitable for evening
History of Scientific Research
Approximately since the middle of the 20th century, this influence has been the subject of focused scientific research. The most famous scientists in this field are probably Colin Pittendrigh, "the father of the biological clock," and Jürgen Aschoff, who are considered co-founders of chronobiology. The first observations in plants, insects, and rodents eventually led to evidence of circadian rhythms in humans as well.
As therapy with sunlight produces good results in treating Seasonal Affective Disorder (SAD) and other deficiency symptoms, an interdisciplinary field of research has developed in which behavioral scientists, biologists, and physicians investigate the effects of light on humans.
Key Discoveries:
- 1991: Russell G. Foster and his colleagues discovered an additional photoreceptor in the eyes of mice that does not participate in the actual visual process but plays a key role in the circadian rhythm.
- 2001: Photosensitive ganglion cells were discovered in the human retina, which helped to further explain the effect of light on the human day/night rhythm.
- 2007: It was established that melanopsin is the chemical substance in the ganglion cells.
Since then, the effect of light on the human circadian rhythm has been described using a spectrum of effects on the internal clock, which vary in strength depending on the wavelength of light.
However, the direction and spatial distribution of light also play a role in this.
Extensive interdisciplinary research in this area has led to today's solid state of knowledge about human needs and dangers that can be caused by light.
Conclusion
The melanopic light effect is a powerful tool for regulating our circadian rhythm, improving sleep, and increasing daytime energy. By understanding how light affects melanopsin and melatonin, we can optimize lighting in our daily lives and improve our health and well-being.
Morning - bright light, evening - darkness and warm light - this is the key to a balanced circadian rhythm and quality sleep.
