This is the role light plays in our health

Light is essential for life on earth - and humans are no exception. However, just how important it is for us is often underestimated. We now know that light has just as great an influence on our bodies and our health as nutrition, sleep or exercise. This article explains the basics you need to know about light in order to use it to your advantage.

This is light

A few facts first: Light is a form of electromagnetic radiation that is emitted by a light source (e.g. sun, light bulb, etc.) in the form of waves. The human eye can only perceive a small part of the entire electromagnetic spectrum. The light spectrum visible to us ranges from 380 to 780 nm and includes all the colors of the rainbow. The light we can perceive is bordered by ultraviolet radiation on the one hand and infrared radiation on the other. For our purposes, the visible blue light (420-490 nm), the visible red light (650-780 nm) and the near-infrared light (from 780 nm), which is not visible to us, are of particular interest.

Important at this point: even if we cannot see certain wavelengths with our eyes, they still have an effect on our body.

Artificial vs. natural light

Natural light is emitted by fire or the sun, for example. Light from fire sources contains a high proportion of red light. Depending on the time of day, the sun has a different composition of the various wavelengths of light. This is because it hits the earth from different angles during the course of the day. While it is mainly the long-wave red wavelengths that reach the earth in the morning and evening, it has a high blue light spectrum in the midday sun. Over the course of evolution, the human body has become accustomed to this sequence and linked it to a series of endogenous processes.

Red light supports regeneration and performance

Over time, however, humans have increasingly shielded themselves from natural light: The majority of our lives nowadays take place indoors; According to a study on the so-called "Indoor Generation" it is even around 90% of our everyday life that we spend indoors. As windows also only let through part of the natural light, the signals that our bodies receive from natural light in modern everyday life are rather low. This is not least due to the fact that we artificially illuminate our homes almost around the clock.

Artificial lightsuch as that from LEDs, smartphones or computersLike natural light, artificial light contains a mix of different wavelengths of light. However, the spectral composition of most sources of artificially generated light is different from that of natural light. Artificial light often has a high proportion of blue light. Regardless of whether a lamp is dimmable or not, this composition of artificial light does not change over the course of the day.

The light signals that our body predominantly receives nowadays therefore no longer have much in common with the natural sequence of light spectra that our body knows from the sun. Unfortunately, they completely mislead our body in its attempt to deduce the time of day from the ambient light. A combination of little sunlight and a lot of artificial light - especially after sunset - can therefore throw our natural biorhythm out of balance. This in turn can lead to a number of undesirable symptoms, such as sleep disorders, stress, chronic fatigue or low mood.

Targeted use of light

Just as a lack of light or the wrong light at the wrong time can have negative effects on us, the supply of certain wavelengths of light can also have positive effects on our bodies. This has now been proven by various studies on Red light or near-infrared light therapy (also Low Level Light Therapy (LLLT) or photobiomodulation (PBM)).

Red light or near-infrared (NIR) has a positive influence on our cellular energy production and therefore also on our cell renewal. As our entire body is made up of cells, the areas that can be influenced by red light are very broad.

For the sake of simplicity, we have therefore divided the proven effects of red light/NIR into four groups and dedicated a separate article to each. Simply click on one of the four groups to find out how it is influenced by red light/NIR and how you can use this specifically for yourself: Skin & Hair, Performance & Regeneration, Pain & Inflammation, Sleep & wake rhythm.

Cover photo: @beaezor via Twenty20

Sources:

WHITTEN, Ari (2018): The Ultimate Guide to Red Light Therapy. Archangel Ink.
WUNSCH, Alexander (2019): The power of light. Why we need light and bad light makes us sick. 1st edition. riva: Munich.
WUNSCH, Alexander; MATUSCHKA, Karsten (2014): A Controlled Trial to Determine the Efficacy of Red and Near-Infrared Light Treatment in Patient Satisfaction, Reduction of Fine Lines, Wrinkles, Skin Roughness, and Intradermal Collagen Density Increase. In: Photomedicine and Laser Surgery. Volume 32, Number 2, Heidelberg: Mary Ann Liebert. 93-100.
YouGov survey (2018) for Velux Group on the indoor behavior of 16,000 homeowners in Northern Europe and North America (including Germany).