Why you shouldn't watch TV with the lights off?

Many people enjoy watching TV with the lights off, and it's easy to understand, as darkness recreates that cinema atmosphere, where all attention is focused on the screen, creating a more immersive experience.

This practice has become common in many homes, especially at the end of the day, when we seek to relax and enjoy our favorite movie or series in a more intimate setting. However, this custom is not limited only to television. Working with the PC monitor, using the tablet or mobile phone in complete darkness has also become common. Whether for convenience or simply to avoid turning on more lights, we often find ourselves in front of these screens without thinking about the consequences, and although it may seem harmless, there are important reasons why this practice is not as advisable as it seems.

What happens when I'm looking at a screen with the light off?

When you look at a screen in a dark environment, your eyes have to deal with a series of adjustments that can be harmful both in the short and long term. If you don't notice the consequences in the short term, or don't attribute them to this practice, you will end up noticing them in the long term.

To better understand what is happening, it is important to know how the eye works and what happens when you subject it to these contrast conditions between the bright light of the screen and the darkness of the environment.

1:posterior segment of eyeball 2:ora serrata 3:ciliary muscle 4:ciliary zonules 5:canal of Schlemm 6:pupil 7:anterior chamber 8:cornea 9:iris 10:lens cortex 11:lens nucleus 12:ciliary process 13:conjunctiva 14:inferior oblique muscle 15:inferior rectus muscle 16:medial rectus muscle 17:retinal arteries and veins 18:optic disc 19:dura mater 20:central retinal artery 21:central retinal vein 22:optic nerve 23:vorticose vein 24:bulbar sheath 25:macula 26:fovea 27:sclera 28:choroid 29:superior rectus muscle 30:retina

The function of the pupil and iris

Let's start with the pupil and iris. The pupil is the opening that allows light into the eye, while the iris is the muscle responsible for regulating its size. This process happens automatically: in dark environments, the pupil dilates to let in as much light as possible, making vision easier. On the other hand, in bright environments, the pupil contracts to prevent too much light from entering the eye. When you turn off all the lights to watch TV or use your mobile phone, your pupils dilate to the maximum as a natural response of the eye, trying to adapt to the darkness and help you see better in low-light conditions.

Now, when you introduce a bright screen into a dark environment, your eyes enter a state of conflict. On the one hand, the bright light of the screen causes the pupil to contract to protect itself from the excess brightness. On the other hand, the darkness of the environment tells the iris to keep the pupil dilated to capture more light. This contrast causes the eyes to constantly strive to adapt to two opposing stimuli. In the short term, this overexertion can cause eye fatigue and increased eye strain, manifesting in symptoms such as headaches, tired eyes, dry eyes, and even blurred vision.

The lens and focus

Then there's the crystalline lens, which is the eye's natural lens responsible for focusing light entering through the pupil and projecting it onto the retina, the light-sensitive layer at the back of the eye. The crystalline lens is flexible, and changes its shape to properly focus on objects at different distances. When you look at a screen in low ambient light, the crystalline lens is also affected. Because the light from the screen is so different from the rest of the environment, the crystalline lens has to continually adjust its focus, which can lead to problems with fluctuating focus or difficulty maintaining sharp vision for extended periods.

Add to this the fact that screens are often filled with small, moving details (especially if you're watching a video or working with text). The constant effort of readjusting focus in these conditions can increase the strain on your eye muscles, which worsens eye fatigue.

The retina and blue light

The retina is one of the most important structures in the eye, converting light into electrical signals that travel to the brain so we can interpret what we're seeing. Within the retina, the macula is the region responsible for central vision and fine details. When you look at a screen in a dark environment, the retina receives disproportionate exposure to the bright light from the screen, especially the blue light, which is common in LED screens.

Blue light penetrates deep into the eye and can damage sensitive cells in the retina over time. This type of light can, in the long term, contribute to the development of macular degeneration, a condition that can severely affect vision.

In addition, exposure to blue light in a dark environment can disrupt the body's circadian rhythms, as it inhibits the production of melatonin, the hormone that regulates sleep, as we already explained in this article. This explains why watching screens before sleeping can cause insomnia or poor quality sleep.

Problems you may have by abusing this bad practice

Short term problems

• Eyestrain or asthenopia: This continual effort to adjust to opposing light conditions leads to eye fatigue. Symptoms include headaches, tired eyes, dry eyes, and blurred vision. The simplest solution is to maintain an adequate level of ambient lighting while looking at screens, which reduces contrast and relieves strain on the eyes. It's also helpful to follow the 20-20-20 rule: Every 20 minutes, take a 20-second break by looking at something 20 feet (6 meters) away.

• Increased eye strain: Eye strain can occur due to the constant strain on the eye muscles to focus on a bright screen in the dark. This strain can lead to eye pain and difficulty focusing at different distances. In the long term, if eye strain is not relieved, it can contribute to the development of more serious vision problems.

Long-term problems

• Macular degeneration: The blue light emitted by LED screens penetrates deep into the eye, affecting the macula , which is the central part of the retina responsible for detailed vision. Over the long term, excessive exposure to blue light in low-light conditions can increase the risk of macular degeneration, a disease that severely affects central and detailed vision. The macula is only about 5 millimeters in diameter, but it is crucial for detailed vision. Despite its small size, any damage to this area can have a significant impact on the quality of your vision.

• Elevated intraocular pressure: Increased eye pressure, when sustained, can affect the retina and optic nerve, which could eventually contribute to more serious problems such as glaucoma. Glaucoma is one of the leading causes of irreversible blindness worldwide. However, with early diagnosis and treatment, it can be controlled and the risk of vision loss can be reduced.

• Development of myopia: Prolonged exposure to screens, especially in inadequate lighting conditions, can cause the development or worsening of myopia, as the eyes are forced to continuously focus on a close distance.

Sleep disturbance

Another major effect of using screens in the dark is sleep disturbance. Blue light inhibits the production of melatonin, the hormone that regulates sleep cycles. This means that if you use screens before bed in a dark environment, your body will have a harder time relaxing and falling asleep.

Curiosity

Did you know that when you look at a bright screen in the dark, you blink less than usual? Blinking helps keep your eyes hydrated, but when you focus on a screen, this reflex decreases by up to 50%. This explains why your eyes may feel dry or irritated after a while in front of a screen. One trick to avoid this is to remind yourself to blink more often or even use artificial tears if you tend to spend a lot of time in front of screens.

Tips to avoid problems

• First of all, obviously, stop exposing yourself to bright screens in low-light conditions, or do so occasionally.
• It is helpful to use blue light filters on your devices or glasses (if you wear them)
• Always adjust the screen brightness to the minimum level at which you can see well.
• Activate “night” modes on devices, which reduce the amount of blue light emitted by the screen.
• To control intraocular pressure, it is important to take regular breaks from screens and perform simple eye exercises, such as blinking more often to keep the eyes lubricated. In cases of high eye pressure, doctors may prescribe eye drops to help reduce pressure.
• Try to reduce screen time at least an hour before bedtime and use night modes or warm lights on your devices to minimize blue light exposure.

And the post is over :(

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