Blue light – what is it?
Blue light is the part of the visible light spectrum with wavelengths of about 400 to 500 nanometers. It accompanies us every day – both natural and artificial. The natural source is, of course, the sun. Artificial light is emitted by the screens of phones, computers, televisions or LED lighting.
During the day, natural blue light has an important function – it improves alertness, concentration and helps the body maintain a proper circadian rhythm. It is thanks to it that the body “knows” that it is daytime and we have the energy to act. However, the problem arises in the evening and at night, when we are exposed to artificial blue light coming from screens or light bulbs.
Excessive exposure to artificial blue light in the evening and at night can disrupt sleep, shift the biological clock, negatively affect metabolism, and lead to eye fatigue and discomfort. This topic is gaining more and more importance in the context of a healthy lifestyle, as well as everyday work at computers and the use of mobile devices.
Blue light and health
Excess artificial blue light can affect not only sleep and eyes, but also the overall functioning of the body. This is because it affects many aspects of our body’s functioning. Their bad action can bring various more or less dangerous consequences.
Circadian rhythm and melatonin
Your body works according to the circadian rhythm – a biological clock that controls, among m.in other things, the sleep-wake cycle, body temperature, blood pressure and hormone levels. Blue light has the greatest effect on the production of melatonin, the sleep hormone that tells the body that it’s time to rest.
Scientific studies show that even dim light in the evening – comparable to a night lamp – can lower melatonin levels and shift the biological clock. The result is more difficult to fall asleep, shortened sleep and long-term circadian rhythm disorders.
Poorer health
Long-term circadian rhythm disturbances have been linked to health problems, including a higher risk of chronic and metabolic diseases. People who work at night or under artificial lighting, such as shift workers, are particularly vulnerable.
Circadian rhythm disturbances and shortened sleep have a direct impact on metabolism. Regular exposure to artificial light at night increases the risk of:
- obesity,
- insulin resistance,
- type 2 diabetes,
- hypertension.
Lack of sleep and circadian rhythm disturbances also affect the hormones responsible for appetite and calorie burning.
The effect of blue light on sleep
Sleep is the area where the effects of blue light are best documented. Evening exposure to screens and artificial lighting can effectively disrupt the natural biological rhythm.
Melatonin – the sleep hormone
Melatonin is responsible for preparing the body for sleep and regeneration. Blue light inhibits its secretion the most, which makes the brain think that it is still daytime. This makes it difficult to fall asleep and makes sleep less restorative.
Delayed falling asleep
Reduced melatonin levels lead to a shift in our “circadian clock”, which means later going to bed and difficulty falling asleep. Even if we spend the right number of hours in bed, we can wake up sleepless and tired.
Imagine a person who spends the evening in front of a laptop or smartphone after work. Although formally lying in bed at the same time as always, exposure to blue light delays falling asleep and shortens the deep sleep phase. As a result, the next day she feels tired, reduced concentration and increased irritability.
Sleep quality
It’s not just about the moment of falling asleep – blue light worsens the quality of sleep. This means that the body does not have a chance to fully regenerate, which translates into poorer functioning during the day, a decrease in concentration and an increased risk of health problems.
What can long-term sleep deprivation lead to?
Long-term sleep deprivation caused by exposure to blue light increases the risk of:
- obesity,
- type 2 diabetes,
- cardiovascular diseases,
- mood disorders and mental well-being.
Blue light and eyes
Long-term exposure to blue light can also affect eyesight. In the daily use of digital devices, eye strain is a major concern.
Digital eye strain
The most common symptoms are dry eyes, irritation, headaches and blurred vision. They are mainly due to prolonged looking at screens, less frequent blinking and glare. Blue light can further impair the comfort of vision.
Lens aging and cataracts
Some studies suggest that blue light may accelerate the aging process of the lens and increase the risk of developing cataracts by acting through oxidative stress. It is a condition in which the balance between free radicals and the oxidants that eliminate them is disturbed. As a result of this stress, healthy cells are damaged.
The main problem for people who use digital devices is eye strain and discomfort. Regular breaks, proper lighting and conscious use of screens significantly improve the comfort of vision.
Blue Light and Children
Children are much more sensitive to blue light than adults.
Children’s eyes
In the youngest, lenses transmit up to 80-90% of blue light, while in adults only about 20%. This means that children’s eyes receive a much higher dose of light energy, which increases sensitivity to negative effects.
Sleep and melatonin
Evening exposure to LED screens suppresses melatonin in children up to twice as much as in adults. The result is later falling asleep and shorter sleep, which affects concentration, well-being and regeneration of the body.
Risk of myopia
Prolonged close viewing of a screen has been linked to an increase in the incidence of myopia in children. Although blue light is not the only factor in itself, its excess puts a strain on the eyes of the youngest.
Expert recommendation
- Limiting the use of screens in the evening,
- Use warm light, preferably without the blue spectrum, in the children’s room
- Encouraging outdoor activities during the day,
- Introducing evening rituals that promote calmness and peaceful sleep.
How to protect yourself from excess artificial blue light?
Fortunately, there are a few simple ways to help reduce your exposure to blue light.
Avoiding bright screens and LED lighting in the evening
Limit the use of phones, tablets, computers and TVs to 1-2 hours before bedtime. Pay attention to the intensity of lighting in the room – bright LED lamps can further inhibit melatonin.
Introduction of “sleep hygiene”
Sleep hygiene includes putting away screens before bed, reading a book in warm light, relaxing music, or meditating. In general, it’s about relaxing in the evening, calming down and doing activities that don’t stimulate us. This helps prepare the body for recovery.
Use of proper lighting
Instead of bright LED bulbs, choose NoBlue bulbs or lights that do not disturb the circadian rhythm. They were tested for blue light emission. Depending on the version, they emit no or minimal blue light. You can function with them without pain and dry eyes and support your sleep in a healthy way. Click on the link below to learn more:
Limiting children’s exposure
Children are particularly sensitive, so it’s important to limit screen use in the evenings, reduce the brightness and blue in the room, and introduce outdoor activities.
Summary
Natural blue light during the day supports alertness, concentration and a normal biological rhythm. The problem arises when we are exposed to artificial light – its excess can disturb sleep, worsen our well-being and strain the eyes.
Avoiding screens and LED lighting in the evening, blocking blue light with glasses, for example, or following sleep hygiene rules are simple steps that help protect health, improve sleep quality and well-being.
During the day, glasses and filters that block artificial blue light emitted, for example, by computer screens, as well as eye hygiene – regular breaks, looking into the distance every dozen or so minutes and appropriate lighting in the workplace will work perfectly.
A conscious approach to blue light protection – both at work and at home – is an investment in health for you and your loved ones.
Bibliography:
1. Harvard Health Publishing. (2024, July 24). Blue light has a dark side. Harvard Health Blog.
https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side?
2. National Center for Biotechnology Information. (2021). Circadian disruption and human health. PubMed Central.
https://pmc.ncbi.nlm.nih.gov/articles/PMC8483747
3. PubMed Central. (2018). Melatonin suppression and sleepiness in children exposed to blue-enriched LED lighting. PubMed Central.
https://pubmed.ncbi.nlm.nih.gov/30556352
4. PubMed Central. (2011). The impact of light from computer monitors on melatonin suppression. PubMed Central.
https://pubmed.ncbi.nlm.nih.gov/21552190
5. PubMed Central. (2020). Metabolic Implications of Exposure to Light at Night. PubMed Central.