Sleep is highly underrated.
It is one of the "pillars" of optimal health... just as important as diet and exercise.
The problem is that humans are sleeping much less than they did in the past.
But that's not the end of it, unfortunately... the quality of our sleep has suffered as well.
It turns out that perhaps the single biggest contributor to our collective sleep problems, is the use of artificial lighting and electronics at night.
These devices emit light of a blue wavelength, which tricks our brains into thinking that it is daytime (5).
Fortunately, this problem has a simple solution and there are a few actionable steps you can take to get rid of that blue light in the evening, potentially improving your health at the same time.
Let me explain how that works...
Our bodies have an internal "clock" that is situated in the brain.
This clock regulates our circadian rhythm, the 24-hour biological cycle that influences many internal functions (8).
Most importantly, it determines when our bodies are primed to stay awake and be productive, and when we feel tired and want to go to sleep (9).
The circadian rhythm isn't 100% accurate. Sometimes it is a bit longer than 24 hours, sometimes a bit shorter.
For this reason, it needs signals from the external environment in order to adjust itself. The most important signals that adjust this internal clock are daylight and darkness.
This actually makes perfect sense... throughout evolution, brightness meant that it was daytime and that we should be awake and get stuff done, while darkness meant that it was time to sleep and recover.
But not all light is equal, it is primarily light of a blue wavelength (blue light) that stimulates sensors in the eye to send signals to the brain's internal clock.
Keep in mind that sunlight and white light contain a mixture of various wavelengths. There is a lot of blue light within (10).
Getting blue light (especially from the sun) in the daytime is very important. It helps us to stay alert, while improving performance and mood (11).
There has even been some success using blue light therapy devices to treat depression, and blue light bulbs in an office can reduce fatigue and improve the mood, performance and sleep of workers (12, 13, 14).
But even though blue light is incredibly beneficial during the day, it can be a complete disaster if we are exposed to it in the evening.
The problem is that modern light bulbs and electronic devices (especially computer monitors), also produce large amounts of blue light and "trick" our brains into thinking that it is daytime.
When it gets dark in the evening, a part of the brain called the pineal gland secretes the hormone melatonin, which signals to our bodies and brains that it is time to get tired and go to sleep.
This means that our bodies don't get the proper signal that it's time to go to sleep, reducing both the quantity and quality of our sleep.
Many have speculated that melatonin-disrupting blue light may be one of the key drivers behind obesity and many of the chronic diseases that are so common today.
However... indoor lighting and electronic devices are a major part of the modern lifestyle and they aren't going away anytime soon.
Fortunately, there is a simple way to block blue light from entering your eyes and disrupting the natural sleep-wake cycle.
Bottom Line: Blue light in the evening tricks the brain into thinking that it is daytime, which inhibits the production of melatonin and reduces both the quantity and quality of sleep.
The easiest and most effective way to avoid blue light in the evening, is to use amber-colored glasses.
These glasses effectively block all blue light, so your brain doesn't get the signal that it is supposed to stay awake.
In one study, people's melatonin levels in the evening were compared during three different lighting conditions (23):
- Dim light
- Bright light
- Bright light with blue-blocking glasses
The graph below shows what happened to a typical subject's melatonin levels...
As you can see, the bright light almost completely suppressed melatonin production, while the dim light did not.
But the people wearing the blue-blocking glasses produced the same amount of melatonin as those being exposed to the dim light. The glasses almost completely blocked the melatonin suppressing effect of the bright light.
Now to the fun part... not only have blue-blocking glasses been shown to increase melatonin, studies also suggest that they can cause major improvements in sleep and mental performance.
In one study, 20 individuals were randomized to use either blue blocking glasses, or glasses that didn't block blue light, for 3 hours before bedtime. The study went on for two weeks (24).
The subjects using the blue-blocking glasses had major improvements in both sleep quality and mood.
These glasses have also been shown to greatly improve sleep in shift workers, when they put them on before bedtime (25).
There was also a study in elderly cataract patients, showing that blue-blocking lenses improved sleep and significantly reduced daytime dysfunction (26).
Overall, it seems pretty clear that using blue-blocking glasses in the evening is effective. Not only does it improve sleep, but it also improves mood and cognitive function.
Of course, this hasn't been studied in a large, long-term study... but given the immense importance of sleep for health, it wouldn't surprise me if these glasses could also help prevent chronic disease and lead to a longer life.
Bottom Line: Studies show that blue-blocking glasses increase melatonin production in the evening, leading to major improvements in sleep and mood.
If you don't want to use these glasses every night, then there are a few other ways to reduce blue light exposure in the evening.
One popular way is to install a program called F.lux on your computer.
This program automatically adjusts the color and brightness of your screen based on your timezone. When it is dark outside, the program effectively blocks all blue light from your computer and gives the screen a faint orange color.
Although I'm not aware of any study on it, many people who use the computer a lot in the evening claim that this program helps them fall asleep.
There are a few other things you may want to consider:
- Turn off all lights in your home 1–2 hours before bedtime.
- Get a red or orange reading lamp, which doesn't emit blue light. Candlelight works well too.
- Keep your bedroom completely dark (highly recommended), or use a sleep mask.
It is also important to expose yourself to plenty of blue light during the day. If you can, go outside during the day and get some natural sunlight.
If that is not an option, consider using a blue light therapy device in the daytime. It is like a strong lamp that simulates the sun and bathes your face and eyes in blue light.
I have a long history of sleeping problems. It usually takes me at least an hour to fall asleep and I tend to wake up frequently throughout the night and feel poorly rested in the morning.
However... about a week ago, I purchased blue-blocking glasses from UVEX that can help block blue light.
I've set a reminder on my phone to always put them on at 8:30 pm. If I'm not home at that time, then I just put them on as soon as I get home in the evening.
After having them on for about 1-2 hours, I start feeling very relaxed and naturally tired.
Since I started using them, I've been falling asleep much faster and waking up refreshed in the morning. My mood has improved significantly and I'm finding it a lot easier to think and write.
I've personally tried a lot of different things in order to sleep better... but using blue-blocking glasses is by far the most effective sleep "hack" I have tried.