What Is the Red Light for on a Headlamp?


Headlamps have so many gizmos and features, and it’s hard to know why you need all of them. The red light feature on many headlamps is a little confusing, especially if you are using the super bright modes and you transition to the red light mode, and you feel you can’t see at all!


So what is the red light for on a headlamp? The red light on a headlamp is intended for preserving your night vision while still providing some light so you can see. Additionally red light modes on a headlamp aren’t as blinding to your friends, so it is ideal when using a headlamp with a group of people.

Cool! Headlamps preserve your night vision. But what does that mean, exactly? Is that a good thing? Is it necessary to make sure you get a headlamp with a red light mode? Lots of good questions–let’s dive into it.

Using a Red Light Headlamp Preserves your Night Vision

Headlamps are so convenient! It’s great to not have to occupy a hand to hold a flashlight, but they do have a downside. When you’re camping, or with a group of people at night, you’ve undoubtedly had the unpleasant experience of having what feels like the equivalent of the sun being blasted in your face by a friend’s headlamp.

After some blinking, your eyes will regain their ability to see, but not without some spots that will persist for several minutes.

Practical Explanation of Why To Use The Red Light Mode

Headlamp manufacturers have been shipping with a red light mode for the exact purpose of preserving your night vision, as well as the night vision of others. Our eyes are less sensitive to low dosages of red light, which means that after you use your red light mode on your headlamp, you will still be able to see if you turn your headlamp off.

Technical Explanation of Why To Use The Red Light Mode

The pupil of the eye changes its dilation rapidly under changing light, and is not the cause of night blindness. Rather, when a light is exposed to our retina, the chemical rhodopsin is bleached, thereby losing its effectiveness. Rhodopsin is an extremely light-sensitive chemical that resides in the rods of our retinas. It takes up to 30 minutes for the rhodopsin in our eyes to fully regenerate.

Rhodopsin is less sensitive to red light, which allows our light perception to persist even when using a red light to see by.

When You Want to Use the Red Light Mode

Great, a headlamp preserves your night vision. So what? Why does that matter?

With a Group of Friends

As I mentioned in the anecdote above, it can be really annoying having your night vision blasted to pieces with the full glory of (what feels like) 2000 billion lumens.

It’s extremely natural to look at something that grabs your attention. Thus, when you have a headlamp on and someone talks to you, it’s easy to look at them. Even experienced campers and hikers will forget and glance at people directly when addressed. Therefore, it is much more courteous to use a red light headlamp in company so that everyone can still see and avoid the unpleasant blindness.

Stargazing

Night vision is super important when you’re looking at the stars. It takes up to 30 minutes for your eyes to be night-vision-itized (new word!), and since many stars shine with a very low light, any amount of light can disrupt your eyes ability to see the dimmer stars.

You will be able to enjoy the fantastic skies better if you use a lower level of light (such as some red light headlamps) to see by, or best, not to use any light at all.

Keeping Your Eyes Ready

I’m probably just weird on this one, but sometimes it’s really amazing to be able to move around at night without any additional light. I remember when I hiked up a mountainside simply by the light of the moon, and it felt exhilarating. In those circumstances the moon can even feel too bright!

Your headlamp is there for tricky scenarios, but you don’t necessarily need it. The red light mode is perfect for this scenario so you can get a little bit of light if you need it, while still being able to navigate without it.

Other Cool Benefits To Using the Red Light Mode

There are actually more benefits to using the red light mode on your headlamp. Let’s take a look.

Hiding From Bugs

As I was doing research, I found that anecdotally, many people have found that bugs are less attracted to the red light than the white light! There isn’t enough information whether it’s the red light itself or if it’s the weaker light output of the red light that causes this. In any case, your red light mode on your headlamp may save you from some bugs. Cool!

I actually did my own research on this and found some interesting results about which headlamp color attracts less bugs! Check out my results here:

Saving a Bit of Battery

This is completely dependent on your headlamp manufacturer, but since the red light mode is typically a weaker light, then you can use your headlamp for longer without needing new batteries (or a recharge if you have a lithium ion headlamp). Additionally, the red light spectrum is easier to reproduce. Again, it completely depends on your manufacturers design, but there is potential that you will be able to use your headlamp for longer.

Red Light Flashing Mode

Flashing red lights grab our attention, constantly. Cars flash red lights when braking, bicyclists attach flashing red lights to the back of their bikes so they will be noticed on the road, cell phone towers have large flashing red lights so airplanes won’t hit them.

Many headlamps have an additional feature with their red light mode, where the red light can flash. If you are in a danger situation, then a flashing red light can help gather attention.

Caveats to The Red Light Mode on a Headlamp

That’s the good. Now what are the gotchas for using the red light mode on a headlamp? Most of the gotchas deal with the reality that headlamp manufacturers slap on the red light feature as an afterthought, more for the point of being able to advertise the red light mode rather than actually providing value.

Disproportionately Weak

Some headlamp red light modes are so small and weak that they do not provide useful illumination. My current headlamp unfortunately falls into this camp.

Strong Red Light Still Affects Night Vision

On the converse, some headlamps try to compensate for the natural lack of sensitivity our eyes have to red light by placing tons of power in the red light. A strong red light can affect your night vision just as much as a white light. Beware of high-powered red lights if you are trying to preserve your night vision.

Often Poorly Designed

I had a headlamp that was decent in most respects, and had a red light mode. Because the red light mode was an afterthought, the red light was so unfocused that it was in effect, shining the red light directly into my eyes. This was almost as good as having no red light at all.

Even if a headlamp has the right brightness you are looking for in a red light, it may suffer from other design issues that make the red light mode useless.

Slightly More Expensive

Headlamps in general are not expensive, but if you buy a medium to high quality headlamp, then adding features such as a red light mode can add to the cost of the headlamp. Many inexpensive headlamps under $25 will throw in a red light mode, but they will vary in quality and usefulness.

Loses Effectiveness Alongside the White Light Mode

Lastly, if you are trying to use your red light mode on your headlamp while others are using their white mode, or if you are needing to switch back and forth between the white light and the red light, then your red light mode is not very effective at all.

Everyone has to be on the same page or else the purposes of using the red light mode are not effective.

Related Questions

Why Do Headlamps Have Green Lights? Green Light is easier for the human eye to see so it works better for illumination, especially when contrast is important, such as when hunting at night. Specially designed green light emitters are also less visible to many animals that are red/green colorblind. Furthermore, some argue that green light is better for preserving night vision because it requires less brightness for the same amount of illumination.

Do They Sell Red Light Only Headlamps? It is more rare to find headlamps with red light only, but they do exist such as this one here.

What Headlamp Should I Buy? I have a headlamp I really like that I wrote about here.

Peter

Peter is a software developer who loves to take every opportunity to go outside that he can get. Peter grew up going on long backpacking excursions with his family every Summer and now enjoys staying at the beautiful Texas State Parks and swimming in the amazing Texas Rivers.

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