Long-term effects of artificial blue light remain unknown

We’ve all heard the warnings: staring at screens before bed disrupts sleep, thanks to the artificial blue light they emit. But is the truth really that simple? 

A recent report by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) suggests that the story might be more complex than we think.

“Our modern society allows for increasing exposure to light in the evening, significantly more than humans have been exposed to for the past approximately 300,000 years of evolution,” noted the experts. 

“In the past couple of decades, the use of mobile devices, e.g., smartphones, laptops, and tablets has increased exponentially, potentially resulting in a significant amount of light entering our pupils after daylight hours.”

Health impacts of short wavelength light

Blue light is a type of visible light detectable by the human eye. It packs more energy, compared to other visible light.

Sunlight is the main source of blue light, but it is also emitted by many artificial sources including the screens of televisions, computers, smartphones, and tablets. This artificial blue light is known as short wavelength light.

The scientists investigated existing studies to understand the impact of short wavelength light on people, both in the short term and long term. They were particularly interested in how SWL might influence our sleep.

Conflicting evidence on blue light and sleep

Surprisingly, the studies have produced mixed results. Some studies found significant negative impacts, while others found little to no effect. 

The experts suggest that this inconsistency might be due to differences in how the studies were conducted, such as the intensity, duration, and timing of blue light exposure, as well as the characteristics of the people involved in the studies. 

“The majority of studies that have assessed circadian disruption due to exposure to light have been conducted in shift workers,” the ICNIRP panel reports. “In these studies, shift workers’ exposure to light during biological night has been taken for granted without direct measurements of their light exposure.”

Artificial blue light and alertness

There is also inconclusive evidence on how short wavelength light affects alertness. While some studies suggest that it can make people less sleepy, the evidence is not yet clear. 

Moreover, the effects might also depend on when people are exposed to it. In some cases, exposure to artificial blue light during the day has been linked to feeling more alert. However, the effects of nighttime exposure on sleep quality and alertness are still unclear.

Lack of consensus on health 

Sleep helps our bodies function properly, including our immune system, memory, and emotions. With the rise of technology, there is concern that the blue light emitted from screens and lights can disrupt sleep. 

However, the ICNIRP team did not find clear agreement among scientists about the long-term health effects of short wavelength light. Some studies suggest there are potential risks, but others find minimal impact.

Call for high-quality research

The expert panel is still unsure whether artificial blue light has negative health consequences. They acknowledge the public’s interest in this topic and emphasize the need for more research.

According to their recommendations, existing studies should be reviewed more thoroughly to gain a better understanding of SWL’s effects. Additionally, they call for well-designed studies to specifically investigate the long-term consequences of repeated exposure to artificial blue light. 

“It has generally been assumed that exposure to SWL at night will cause alertness and affect sleep quality,” wrote the researchers. “However, due to limited data and conflicting results regarding effects on alertness, sleepiness, and sleep it is not possible to reach a conclusion about effects on these outcomes.” 

“This is the case for both nighttime and daytime exposure. Thus, more high-quality experimental studies are needed to answer the question of whether SWL exposure at night affects alertness and sleep more than exposure at other times of the day.”

The full statement from ICNIRP is published  in the journal Health Physics.

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