Over the past decade, researchers have investigated whether artificial light – especially wavelengths of blue light – pose a risk to human health.
You may have heard that too much screen time in the evening is bad for you, and it's true the blue light emitted by devices like phones and tablets can interfere with your sleep.
But blue light is not that bad – and here's why.
Blind mice feel blue light
In 2002, researchers identified a new type of photoreceptor cell in the eye when the visually blind mice they studied could still respond to some wavelengths of light.
The cells, called Intrinsically Photo Sensitive Retinal Ganglion Cells (ipRGCs), respond to the light to regulate our circadian clock – not to form images that spell and cones in our eyes do.
By discovering how much light is present in our environment, the cells can communicate with our brain and body that it's time or time to sleep and thereby put our circadian clock, according to neuroscience Stuart Peirson from Oxford University.
"We have been developed to expect light for a certain part of the day and it optimizes our physiology and behavior to predict changes in our environment," said Dr. Peirson.
IpRGCs are sensitive to light wavelengths of 480 nanometers – just in the blue light spectrum.
But Dr. Peirson said, in fact, that IpRGCs can detect most wavelengths of light, and it can all interfere with our circadian clock.
Disturb your circadian clock
In modern society, artificial is all-encompassing – and it is consistent with our body's expected light moon cycle, according to psychologist Lora Wu of Massey University, who contributed to a report of blue light released this week by the Royal Society Te Aparangi in New Zealand.
"We have a master clock in our brain, which is determined by light exposure to the eye. And every body and body in your body also has an internal clock," said Dr. Wu.
"If your main watch is not synchronized with your various internal clocks, it can lead to circadian desynchronism, which has major health effects."
These contradictory signals between your watches can lead to changes in your physiology and behavior – such as your mood and metabolism.
Shift workers – who often need to sleep and eat at odd times – are the main candidates for circadian desynchrony.
And Dr. Wu generally said that it is very difficult for people to adapt to such disorders, with one exception.
"Sometimes people think if you're a permanent shift worker, you can essentially turn the clock and then be awake and work at night and fall asleep during the day. But the only place where it has been shown is in offshore oil platforms," she said
On offshore rigs, it is possible to have complete control over the physical and social environment of the workers, so their meals, lighting exposure and socialization pass all over to night time.
"In the case of [offshore rigs] You may see some adaptation in daily life, says Dr. Wu.
"But generally, workers do not change very well at all, because people tend to return to a daytime schedule when they are in their days."
In the case of blue light, it is the time of your exposure that is important to your health.
"You actually need [blue light] in the morning to help your watch sync, "said Dr. Wu.
And you can get this natural from daylight.
But there is solid proof that if you get too much blue light before bed from devices like phones or tablets or from black rays, it will interfere with your body clock.
And that's because ipRGC in your eye – very sensitive to blue light – says to your brain, it's not time to sleep yet.
Blue light and mental illness
Regulated exposure to artificial light has been used to treat seasonal disease (SAD) for a long time, and Dr. Wu said that blue light treatment is now a standard treatment for major depressive disease as well.
"It has proved very effective to add artificial light to standard treatments for depression," she said.
People with mental health problems are more likely to get a disturbed daily rhythm, said Dr. Wu, including sleeping during the day or staying up late in the evening.
"We see a loss of rhythmicity in conditions such as bipolar disorder and even suicide outcomes – basically any form of behavioral or mental illness," she said.
Because the circadian rhythms of people with depression are muted, exposure to blue light in the morning – as well as limiting it at night – can help restore the body's natural rhythm, which can improve sleep and mood.
And getting an early night can also help.
Australian research published earlier this year suggested that SSRI antidepressants were less effective for night nuggets compared to early risers.
SSRIs or selective serotonin reuptake inhibitors work by increasing how your circadian clock responds to the light, which is supposed to stabilize if you wake up and sleep at normal times.
But since nightworms are exposed to more light in the evening – often blue light from the screens – the SSRIs can set the time longer and stop the treatment that works for the underlying mental state.
And poor sleep quality and lack of routine can contribute to poor physical and mental health and put an unhealthy bike going on.
As an acknowledgment of the links between sleep quality and good health, a survey on sleep health in Australia was launched in September 2018.
UV illuminates the real issue in eye disease
When investigating how blue light affects human health, conversation becomes inevitable if blue light is harmful to your eyes.
According to the Royal Society Te Aparangi report, high intensity light intensity can cause serious damage to the retina, and the blue light transmitted from phone and computer screens is well below the harmful intensity.
The report also suggests that there are no signs of a link between blue light exposure and eye disease including macular degeneration.
By 2017, vitamin companies sold products that claimed to protect the eyes of the children from the blue light emitted from their electronic devices – claims dismissed as "ridiculous" by ophthalmologists.
People, especially parents, should be more concerned about UV light, according to ophthalmologist Shanel Sharma, member of the Royal Australian and New Zealand College of Ophthalmologist Public Health Committee.
"Blue light gets a lot of attention, but it is not related to eye diseases," Sharma said.
"It's UV light that causes a lot of dazzling eye diseases."
Dr. Sharma is an exercise pediatric ophthalmologist in Sydney and regularly treats children with UV-light eye damage.
She said that while parents often think about protecting their children's skin, eye protection is not highly prioritized.
Dimm the light at night or go camping
There are some relatively simple changes that humans can do for their behavior to minimize the risks of bell-outbreaks of blue light at night, said Dr. Wu's psychologist.
"Try to get daylight in the morning, limit the blue light from units at night and replace cool / white-colored lights with warmer colored," she said.
A study showed that going camping for the weekend and avoiding all artificial light sources could restore your circadian clock.
Camping is not the whole solution, of course.
But the research reinforces the importance of the natural light-dark cycle in regulating our body blocks.