Blue light – The killer of our body clock

How phones are waking up our fish brains

Writer: Ben Freeman
Editor: Maria Stoica
Artist: Wenanlan Jin


I’m sure you’ve heard of this phenomenon everywhere: in the news, on billboards, and maybe even more ironically, on your phones. We know blue light is harmful when we’re exposed to it before we go to sleep, but have you ever wondered why? 

Well, to answer this question we have to go back a few years…. Okay, a few million years, to when it was simply aquatic life that inhabited earth. During this period, our body clock (or circadian rhythms, if we’re trying to be smart) began to develop. The body began to develop cryptochromes; by sensing the levels of blue light in the water (the only light that can penetrate water), cryptochromes kept track of day and night and changed the body’s activity appropriately. For example, when cryptochromes detected a decrease in blue light levels, they would prompt a decrease in the fish’s metabolic rate and an increase in its melatonin production. 

Fast forward a few million years and mammals began to evolve from the same fish, retaining the blue light sensitive cryptochromes. However, mammals’ cryptochromes became light independent, because they were exposed to the whole spectrum of light. Instead, mammals require a set amount of sleep dependent on the body’s activities, irrespective of what time of day it was, which explains why some teenagers are close enough to being nocturnal. 

Life ran perfectly well for another few million years until the development of technology, specifically monitors on phones, tablets and laptops. The artificial light these devices emit is composed primarily of blue light, which activates a part of the cryptochrome that hasn’t been in use for millions of years. As a result, your brain is tricked into believing  that the sun is coming up and responds by releasing signals to the body to wake up.

This doesn’t just have short term effects on the body. With the use of this blue light, the body is essentially running on two body clocks: one that is built within all mammals and is independent of light, and another that is archaic and solely responds to blue light. Mixing these two body clocks has catastrophic effects on the body, mainly on the production of melatonin. The body produces excessively large amounts of melatonin in response to the blue light emitted by monitors at night. This negatively impacts both your body’s core functions and your reproductive system.  If you go to sleep just as your body is waking up, the increased core body temperature, metabolic rate and brain activity can wreak havoc on your body’s functioning in the long run for when you actually want to be awake. 

So what can you do to stop this? Well, as it turns out, blue light can be very beneficial at the right times of the day. Research has shown that blue light can increase alertness, boost your memory and cognitive function and elevate your mood. So exposure to blue light in the morning can keep you alert and functioning for the whole day. So put down that morning coffee, stop doing assignments at 1am, and become an early bird.

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