You may have heard Andrew Huberman speak about the benefits of getting sunlight in the day and reducing light exposure at night. Like many things in life, light is a double edged sword, so we wanted to break down when it’s good and when it’s bad for you by delving into a 2019 study by Christine Blum.
How does light affect my body?
We all have a 24-hour, “biological clock” called the circadian rhythm. This “clock” does many things, but most famously tells our body when to go to sleep and when to wake up. This is done through a series of inputs that result in specific hormone secretion that makes us sleepy or alert.
The largest of these inputs is light. We evolved hundreds of thousands of years to wake up when the sun rises and start to wind down after it sets. Our bodies are (or were) attuned to the natural 24-hour light cycle. While not getting too nitty gritty, this is accomplished through the delivery of light (among which Blue Light is the most powerful) to our eyes (more specifically, our retinas).
When we wake up and go outside, Blue Light from the sun floods our eyes and our bodies interpret this as time to wake up. This begins our clock for the day. The study goes on to breakdown how light affects our clock, by stating: “Two effects of light have been interrogated extensively in human circadian and sleep research: (1) the acute suppression of melatonin in response to light exposure and (2) the ability of light exposure to shift circadian phase.”
We’ll break down each of the two below, starting with the latter.
The ability of light exposure to shift circadian phase
The effects of light on your circadian rhythm really depend on what time of day it is, either moving it forward or delaying it. The relationship is best shown in the phase response curve (PRC) below:
This graph shows that generally speaking, light received in the morning (early parts of the circadian phase) advance the clock and light received at night delay it. You can also see that the delay range is deeper than the advance range, meaning our clock is more sensitive to light at night than in the morning.
An example of this in real life is when you have an early morning flight and turn the lights on in your room right as you wake up. You’re much more likely to be alert than if you kept the lights off. Conversely, if you’re up late playing video games you’re likely to not feel as tired as the Blue Light from your LED screen bathes your eyes.
The acute suppression of melatonin in response to light exposure
Melatonin is the sleep hormone our body releases when it’s time to go to bed. It’s integral in our sleep cycle, so much so that companies nowadays are selling supplements. You may have seen melatonin gummies on the shelves at Target promising you a good night’s rest.
The research shows that light exposure at night delays melatonin suppression, causing you to stay up later or not be as tired. Of the visible spectrum of light, Blue Light is the highest energy (380 nanometers to 500 nanometers). It’s also one of the most prominent lightwaves emitted from our screens. Research points to Blue Light out of all the lights having the biggest effect on our sleep cycle.
That’s all great, but when is light good and when is it bad?
The study mentions that increased light exposure during the day time, specifically right when you wake up, leads to higher alertness and a greater night's rest. This follows along the reasoning above in that it starts your biological clock quicker.
Conversely, light exposure at night is shown to increase sleep latency (longer time to fall asleep), reduce nighttime sleepiness, melatonin suppression, sleep duration, sleep quality, AND next morning alertness. This means we should be very careful about light exposure at night.
If the sun is down, where are we getting light from at night?
Now this seems like a silly question, but it’s important to point out the obvious. We as a species have been spending more and more time on devices ever since Apple decided to release the iPhone. Since:
- Light exposure at night affects you more than light exposure during the day
- Light exposure at night mostly comes from our electronic devices
It is extremely important that people have protection against harmful light at night! There are a few different ways to go about this:
- Live like a caveman with no devices at night
- Wear protective Blue Light blocking eyewear when going on your devices
- Use a BlueBuffer and have zero change to your lifestyle
What is BlueBuffer you may ask? It’s our Blue Light blocking iPhone screen case that keeps your eyes and screen safe from harm. With specifically tempered amber glass, BlueBuffer is proven to block Blue Light (check it out in real time here!).
Now we’d love for you to look into us, but most important than all we wanted to make you aware of the dangers of light at night. Get some protection, or keep the thought in the back of your mind in the future.
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