What Is Blue Light? And How Does It Affect Your Health?
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What Is Blue Light? And How Does It Affect Your Health?

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What Is Blue Light? And How Does It Affect Your Health?

Posted a year ago

Brian Stanton

Brian Stanton


Dr. Kevin R. Gendreau

Dr. Kevin R. Gendreau

Author and Scientific Reviewer

Expert Approved

Blue light is all around you. Is it a hazard to your health?

It depends. If your night time ritual is bathed in blue light, your sleep might be suffering. 

But if you’re blocking blue light 24/7, that’s not ideal either. Blue light is crucial for resetting your 24-hour wake-sleep cycle so you can be alert (or relaxed) at the proper times.  

So, what are the pros and cons of blue light exposure? Is blue light bad for your eyes? And are blue light glasses worth it? 

Let’s find out. 

What Is Blue Light?

Blue light is a form of electromagnetic radiation visible to the human eye. 

Most forms of electromagnetic radiation (UV rays, radiowaves, infrared, microwaves, etc.) are invisible to the human eye. In fact, our eyes can only see wavelengths between about 380 (violet) to 700 (red) nanometers. 

Blue light falls in the middle (400-500 nanometers) of the visible light spectrum.[*] Oversimplified fact: the sky is blue because the atmosphere scatters blue light waves from sunlight more than other forms of visible light. 

Blue light is ubiquitous. It’s part of sunlight, light fixtures, headlights, and light-emitting devices like the one you’re using now. 

White light contains the full visible spectrum, including blue light. To avoid blue light waves, red light is your safest bet. 

Is Blue Light Bad for Your Eyes?

There’s lots of science (and controversy) on this topic. Let’s simplify. 

Here’s the punchline: while excessive blue light exposure can be dangerous, everyday levels of exposure don’t appear to damage the eye.[*

Excessive exposure might mean staring at the sun. Most people with a room temperature IQ or higher know that’s a bad idea. (UV rays from sunlight also cause eye damage.)

Excessive blue light might also come from:

  • Movie projectors (projectionists, be careful!)
  • Xenon headlights
  • Welding equipment
  • That uncomfortably bright light dentists use

Provided you aren’t frequently exposed to these sources, your eyes should be okay. 

Also, if normal levels of blue light caused eye damage, wearing blue-blocking glasses would prevent this damage. But the data suggest that isn’t the case.[*

Benefits of Blue Light Exposure

Blue light has become a villain in the wellness world. Like a telemarketer, we always look to block it. 

But if you always block blue light, you’re blocking a critical regulator of the circadian rhythm.[*] (Our 24-hour wake-sleep cycle.) Here’s how blue light wakes you up:

  1. Blue light hits your retina, activating a brain structure called the suprachiasmatic nucleus (SCN)
  2. The SCN shuts down melatonin (your sleep hormone) and boosts alertness hormones
  3. You get the memo: sleepy time is over—time to wake up!

Daytime light exposure also helps you sleep later. In one study, researchers found that combining blue light exposure with a high-protein breakfast boosted melatonin later at night.[*

Along with the foundational benefits on daily rhythms, blue light exposure may also improve:

  • Various skin conditions, including acne[*]
  • Memory and learning[*]
  • Reaction times while driving (at the expense of driving accuracy—oops!)[*]

Okay, let’s review when you should block blue light now.  

Blue Light and Sleep

For most of human history, the sun dictated our daily rhythms. The sunrise would stimulate our waking, and the sunset would wind us down for sleep. 

Modern technology changed all that. Lights and light-emitting devices now allow humans to stay active well into the witching hours.

Remember, blue light wakes you up. Not ideal if you’re preparing for bed. 

Specifically, blue light suppresses your sleep hormone, melatonin.[*] Less melatonin means a harder time falling and staying asleep. 

But melatonin suppression is just the tip of the blue light-berg. Blue light at night dysregulates the circadian rhythm, which dysregulates big chunks of the human genome.[*

That’s bad news for health and longevity. A broken circadian rhythm (i.e., poor sleep, melatonin issues, etc.) can increase the risk of:

Sleep disturbances are also linked to shifts in ghrelin (hunger hormone) and cortisol (stress hormone), making lifestyle changes nearly impossible without adequate rest.[*][*]

The takeaway? Minimize blue light exposure at night to live as nature intended. 

Do Blue Light Glasses Work?

It depends on your definition of “work.” Blue light glasses seem to help some folks, but they’re not a panacea. 

It’s been shown, for instance, that glasses with an orange or yellow tint block 67-99.8% of blue light.[*] Nonetheless, the research on blue light glasses for sleep is inconclusive.[*

One explanation? Many clear blue light filtering glasses allow substantial amounts of blue light through. 

Another? People may use the glasses as a “free pass” to watch TV or check email while the rest of the world sleeps, obliterating any potential benefit.  

If you’re on the fence, experiment. Try wearing them at night for a week (changing no other behaviors) and see if your sleep improves. 

There’s no downside to trying. Looking like Elton John isn’t a downside, is it? 

Top 5 Tips to Reduce Blue Light Exposure at Night

Want to minimize blue light at night to massage your circadian rhythm and sleep like a baby? Try these tips. 

#1: Mind your lighting

Blue light is not your friend after dark. Surround yourself instead with the longer, more soothing wavelengths of red light. 

Himalayan salt lamps are an effective yet affordable option. If you’re extra motivated, install bulbs that automatically red-shift at twilight. 

#2: Minimize screen time

Screens are the other primary night time source of blue light. To avoid them, power down at least one hour before bed. 

As a bonus, avoiding email at night will help you stay calmer than a Buddhist monk after a cup of chamomile tea. 

#3: Wear blue light glasses

Despite your best efforts, screens will invade your evening. Throw on blue light glasses to minimize their effects on sleep. 

Choose a tinted blue blocker (like the yellow-tinted lenses from Boncharge) for maximum efficacy. Fun social experiment: wear them on date nights and see what happens.  

#4: Turn on night-mode 

Most smart devices have low-blue light settings for night time comfort. Also, select the “warm” color setting on your TV to red-shift your viewing experience. 

#5: Keep it dark

Keep your bedroom as dark as possible. (Wear a sleep mask if need be.) Even a tiny amount of light can impair sleep. 

Blue Light Isn’t Always Bad

It’s not. We need blue light to reset our circadian rhythm and wake us up.

But blue light at night hinders sleep. So do your best to avoid it then. 

Blue light at night is bad. Blue light during the day is good. 

That’s the take-home message. Simple enough, right? 

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