Many of us spend hours and hours every day in front of a screen. Whether you’re sitting at your laptop for work, messaging friends on your smartphone or just watching tv in the evening - screens are part of everyday life and for most of us, essential!
But through screen time, you are exposed to harmful blue light that is emitted from digital devices. This exposure can have several negative impacts on your health and wellbeing, including loss of sleep, digital eye strain, macular degeneration, premature skin ageing, and development of long-term lifestyle conditions such as heart disease, diabetes, and obesity.
Blue Light and Sleep
The natural cycle of waking up and sleeping is regulated by the presence of natural blue light and its absence, respectively. When you’re not exposed to blue light because the sun has set, your brain triggers the secretion of melatonin, the hormone that lowers your body temperature and makes you feel drowsy.
On the other hand, when the sun rises, blue light penetrates into the eye to a photoreceptor known as melanopsin. This causes a chemical reaction that triggers the brain to stop the production of melatonin. Your body temperature then rises, and you start waking up. Blue light is responsible for keeping you alert during the day, lifting your moods, and boosting your brain function.
Artificial exposure to blue light at night from devices interferes with this natural flow of events. If you extend your working hours, watch a movie, or find yourself tumbling into the endless rabbit hole of Instagram at night, your brain is tricked into thinking it’s still day time. It then suppresses the production of melatonin and delays sleep. This is the reason you may find it difficult to sleep after screen time at night.
The normal sleep-wake cycle of a healthy adult is about 24 hours. Repeatedly staying up while exposing yourself to blue light at night, lengthens this cycle. This means that you’ll have a hard time getting sleep even when you don’t have screen time. It also means that you’ll find it difficult to stay asleep for long. The body, therefore, doesn’t get enough rest and this affects your productivity.
Blue light and Digital Eye StrainHave you ever experienced sore, dry, and red eyes, headaches, blurry vision, sore neck, and shoulders after spending a long time on your computer? If yes, then you suffered from a classic case of digital eye strain or computer vision syndrome (CVS). It is the most common condition associated with prolonged exposure to blue light.
As we mentioned earlier, blue light penetrates the photoreceptor melanopsin which is found in the retina. The eye is very sensitive to blue light for the purposes of regulating the circadian rhythm. However, the lengths most people stare at screens is more than the eyes were meant to take at such proximity. They quickly suffer from fatigue which manifests as digital eye strain. Needless to say, you can’t perform optimally if you’re having the issues that come with CVS.
Blue Light and Macular Degeneration
Macular degeneration is a sight problem that often comes with age. It involves the breaking down of cells at the centre of the retina leading to blurred vision or in serious cases, blindness. Overexposure to blue light accelerates the breaking down of these cells. The result is that you develop this condition way before your time!
Blue Light and your Skin
Apart from your eyes and sleep, blue light also affects your skin. Holding your smartphone right next to your face while browsing and sitting close to your computer or television screen exposes you to too much blue light. It activates a process known as photo-ageing where your skin ages faster due to high-energy light rays that it’s exposed to.
Photo-aging due to blue light occurs in three ways:
- The weakening of elasticity – Just as easily as blue light penetrates to the inner eye, it also penetrates into the skin in the same way. When it does, the skin’s rate of producing oxygen reactive species is increased. This causes the destruction of DNA in the skin and the breakdown of elastin and collagen. Collagen and elastin are the tissues in the skin that keep it firm and young-looking. If they break down, the skin sags and develops wrinkles which gives it the appearance of age.
- Hyperpigmentation- Exposing skin to blue light causes it to pigment. Blue light depletes melanocytes which produce melanin that gives your skin its natural colour. The remaining melanocytes become larger and their distribution more concentrated. This leads to the appearance of age spots. Dermatologists have even noticed that hyperpigmentation is now common on the sides of the face where people hold their phones while on calls instead of the cheeks as was common before.
- Inflammation- Skin that is overexposed to blue light often reddens and swells and this is called inflammation. Inflammation degrades cells and reduces the production of collagen and this reduces the skin’s elasticity. It also hinders the body from repairing damages to the skin so age shows faster.
Blue Light and DiabetesExposure to blue light at night causes insulin resistance so the insulin in your body is not able to act on glucose. This raises your blood sugar levels because the glucose continues accumulating and eventually causes diabetes.
A 2019 study done by the University of Strasbourg and the University of Amsterdam on male rats showed that after an hour of exposure to nocturnal blue light, their blood sugar levels shot up and raised their sugar consumption. They developed a higher tolerance for glucose which is a sign of pre-diabetes in humans.
This study showed that if you are exposed to blue light at night, you are more likely to be tempted to eat sugary food. Perhaps now you know why sneaking in that midnight treat is so irresistible!
If this goes on for a long time, you might find yourself developing diabetes.
Blue Light and ObesityWe already discussed how blue light is the reason you are having a hard time falling asleep. Lack of sufficient and quality sleep leads to the accumulation of body fat and cortisol hormone levels. Higher cortisol levels are often the cause of the accumulation of belly fat.
Blue light can also contribute to the lead up to obesity because it causes leptin resistance. Leptin is a hormone responsible for reducing the intake of food and balancing body weight. It’s the hormone that signals to the body that it’s had enough food and causes the feeling of satiety. Leptin resistance, therefore, will cause a person to eat excessively because their body doesn’t tell them that it’s time to stop.
Blue Light and Cardiovascular Diseases
Blue light upsets the natural body clock and this has far-reaching consequences including the development of cardiovascular diseases. Melatonin, the hormone that helps you fall asleep, is beneficial to the cardiovascular system in several ways:
- It reduces your levels of cholesterol
- It lowers your blood pressure
- It prevents the hardening of your arteries
- It helps in the relaxation and constriction of heart muscles
- It reduces the damage of tissues due to heart attacks and strokes
- It reduces inflammation
Getting poor sleep has been linked to higher incidences of heart failure, heart attacks, clogged arteries, strokes, and high blood pressure. Therefore, staying up to binge-watch movies or to meet work deadlines is not doing your heart any good!