Screentime and Blue Light

By Eva Zheng

Technology is a vital part of a teenager's life. Teenagers use it for entertainment (i.e., social media, games, streaming services) and educational purposes. Adolescents can collaborate on projects, practice supplementary material, and communicate with their teachers. On average, US teens spend a whopping seven hours per day on their screen. This is a sharp contrast from the AHA's (American Heart Association) recommended time- two hours per day.

Although we have been told many times that looking at screens for prolonged periods can be damaging for our eyes, the situation could be worse than we thought. Blue light, which exists from 460-480mm, could have significant changes to our bodily functions.

The light spectrum is composed of different wavelengths of energy created from a light source. It consists of UV, visible and infrared light with visible light is the only part detectable by eye. These colors include red, orange, yellow, green, and blue light rays. There is an inverse relationship between the wavelength of the rays and the amount of energy they have. Specifically, blue light rays have short wavelengths and very high energy.

Blue light is all around us in the world- sunlight is the most significant source of blue light. However, in today's world, there are many sources of artificial blue light, which include displays on tablets, phones, and laptops. Manufacturers also use brighter LED screens because they are more efficient, thinner, and longer-lasting.

Our circadian rhythm is an internal system that tells the body when to eat/sleep in a roughly 24-hour cycle. It is essential for determining one's natural sleeping/feeding patterns. Daylight is what keeps one's internal clock aligned with the environment.

When it starts getting dark, the pineal gland inside our brain tells our body to create sleep hormones, such as melatonin. Melatonin is a hormone that is naturally made by the pineal gland and regulates the sleep-wake cycle. However, when artificial light is added, our retina receives light irregularly and does not know when to sleep. The irregular exposure of light to the retina causes the production of melanin to halt, which is why the body does not know when to sleep. Fluorescent and Led bulbs have blue light- which suppresses the amount of melatonin for more than any other color of light, as your body starts to associate this light with daylight. Scientists believe that this is because of its shorter wavelengths.

Well, how can we fix this problem? Here are a couple of suggestions to limit your exposure to a blue night.

  1. Download a blue light filter app for your devices. An example of this is F.lux, which is free software that automatically adjusts your computer display to your time of day.

  2. Get blue light filtering glasses whenever you are looking into a screen.

  3. Try to limit your exposure to devices right before sleep. Set a timer for around an hour before you sleep so you can limit your usage.

Enrichment questions

1. What is melatonin? What is its specific function?

  • Melatonin is a natural hormone released by the pineal gland that your brain produces to respond to darkness. It is generally inactive during the day, but when the day becomes darker, the suprachiasmatic nucleus or nuclei (SCN) turns on your pineal. As a result, the melatonin levels in your blood rise quickly, and you feel less alert.

2. What are the other possible side effects of using your phone for too long?

  • Excessive screen time can cause a lack of exercise and a sedentary lifestyle. A healthy lifestyle requires a balance of screen time and exercise. It can also lead to less information processing skills and reduced impulse inhibition.


Blue Light: What is it and How Does it Affect Us? -- Occupational Health & Safety