The consensus among over 200 scientists is that the unnatural properties of artificial lighting are behind serious health issues, and that “circadian lighting” should be implemented in buildings, a technology that currently makes up only 0.5% of installed lighting systems. They also recommend incorporating the circadian properties of electrical lighting into standards. The document gathers 24 statements about the impact of light on circadian rhythms and health, agreed upon by more than two-thirds of the total 248 global scientists who have published 2,697 articles on light and circadian clocks in peer-reviewed journals since 2008. The study emphasizes the importance of regular exposure to natural light during the day to strengthen circadian rhythms. It also highlights the negative effects of exposure to light containing blue energy in the evening and at night, as it can disrupt sleep, delay circadian rhythms, and increase the risk of health problems. Current statistics show that only 0.5% of sold lighting fixtures have properties that do not disrupt and, in fact, support circadian rhythms. The document illustrates that there is now enough evidence to implement circadian lighting, which adjusts the intensity and spectrum of light throughout the day and night, as a standard in guidelines and recommendations for public institutions and construction projects.
Bright light during the day promotes the proper functioning of circadian rhythms and enhances alertness and cognitive functions
Increasing the light intensity during the day indoors promotes circadian rhythms and reduces daytime sleepiness, thereby also promoting alertness. It is also important to look at the blue content of the light hitting the retina, as this factor is more important than the correlated colour temperature of the light source itself for determining health effects. Evidence also supports the introduction of circadian lighting, which regulates light intensity and blue content during the day and night.
Disruption of circadian rhythms in the event of improper light exposure leads to health problems
Stable circadian rhythms are essential for maintaining good health, but disrupting them can significantly impair health. Increased light intensity at night increases disruption of circadian rhythms and suppresses nocturnal melatonin production. Repeated and prolonged exposure to night-time light can lead to an increased risk of breast cancer, obesity, diabetes and sleep disorders. LED sources with a high blue light component should carry a warning about the harmfulness of their use in the evening and at night.
