LED or light-emitting diode is the latest and most energy-efficient source of light to date. LEDs are a great invention. They’re cheap, long-lasting, very bright and extremely effective. Compared to regular incandescent light bulbs, LEDs save at least 75 per cent of energy while lasting up to 25 times longer. A 4W LED bulb is roughly equivalent to a 40W incandescent light bulb. And that’s all great! Until you look at what scientific research has to say about long-term exposure to it.

The problem is that the LEDs are producing high amounts of something called Blue Light. You may worry about what exactly is Blue light.

To put it shortly, the spectrum of visible light consists of several colours. Red, Orange, Yellow, Green, Blue, Indigo, Violet or as some may know it ROY G BIV. Together it makes the light that surrounds us during the day. Blue light sits between green and indigo with a wavelength between 450 and 495 nm (nanometers). It has short but high-energy waves making it very powerful (almost as powerful as UV light, which is considered harmful to your eyes and skin).

During the day it can be pretty helpful. It boosts your attention, raises your mood and helps you sleep better at night. In fact, Scientists recommend exposure to bright light during the day.

Everyone has an internal clock built into their body. This clock makes sure to put you to sleep when the night comes and to wake you up in the morning. It is called a circadian rhythm. The average length of the rhythm is about 24 and one-quarter hours. Exposure to daylight helps to keep a person's internal clock aligned with the environment.

And here comes the twitch.

Thanks to the affordable, highly energy-efficient artificial lighting making its way to our homes, we are surrounded by bright day-like lights even at night! And it messes up with our circadian rhythm! Yay! We can now stay up the whole night doing things we didn’t have time for during the day, or even just watch the TV all night long and expose ourselves to even MORE BLUE LIGHT and therefore get even less tired.

(Just… Please don’t do that:/)

Thanks to something called adenosine, you wouldn’t last very long. Even if you would stay awake for a few days after all your body would put you to sleep. Adenosine is a neurotransmitter in your brain that accumulates during the day and increases your need to sleep, also called sleep pressure or sleep drive. For receptors to get cleaned, your body needs to sleep.

Fun Fact! That’s how drinking a coffee or tea prevents you from falling asleep. The caffeine contained in it blocks the receptors and adenosine can’t accumulate on them therefore the sleep pressure does not increase. The effect of caffeine can last in some individuals for up to 12–14 hours.

Exposure to it after the sun goes down causes your circadian rhythm to shift for as much as 3 hours, some studies suggest. After sunset, the main source of blue light is gone, your body detects it and melatonin starts to be produced. This hormone helps to decrease the heart rate and increases tiredness in order to help you fall asleep.

However, when you light up the LED bulb hanging above you, blue light is once again emitted. It’s telling your body “Hey, the sun is still shining so it must be the day!” And the secretion of melatonin gets delayed.

LED light bulbs are not the only ones to blame. In today's digital era, we tend to use our phones or computers extensively during bedtime.

Unless you’re using a phone from the 1900s or early 2000s, your phone probably uses LCD or, already mentioned, LED display. And both of them produce significant amounts of blue light.

One study even found that using phone 2 hours before going to bed blocks melatonin by 25%. Another study looked at reading a book during the evening hours. One group read a paper book but the other read the book on an iPad. The iPad group had 50% less melatonin compared to the paper book group. In other words, reading a digital book delayed melatonin rise by 3 hours. Other than that, individuals who used an iPad for reading, have lost significant amounts of REM (Rapid Eye Movement) sleep. And effect lasted for a few upcoming nights.

This story is not about ways how to improve your sleep. It’s just focused on the effects of blue light. So what can you do to avoid adverse effects?

Some studies show that even a small bedside lamp can interfere with melatonin rise. A small light with an intensity of 8–10 lux can trick your mind into thinking the sun is still shining. Unfortunately, a regular night lamp has about 20–80 lux and most of us spend the evening hours underneath much stronger lights with an intensity of about 200 lux.

According to my research on the internet, warmer LEDs tend to produce less blue light, although still higher amounts compared to incandescent light bulbs.

In the end, the incandescent night light might not be such a bad idea even with its higher consumption. Try to dim your lights as much as possible, whether it’s LED or regular bulbs, and prefer LEDs with warmer tones in the evening.

As already mentioned, the screens of our phones produce high amounts of blue light which interfere with our sleep cycle.

Use blue light filters on your devices if available. This feature dims the blue diode on the screen and therefore your device produces less blue light. And don’t forget to dim the brightness! But still, try not to use electronic devices at all, switch a late-night movie for an interesting book and the quality of your sleep will get better.

In conclusion, modern technologies are here to help us, but we need to learn how to use them to our advantage, not our disadvantage.

Thank you for reading. The credit goes to the book “Why we sleep” for inspiring me for diving into this topic.

where the future is written

Chemistry student in Slovakia. Reading a lot of scientific news and writing about them