How to Use Red Light with Your Digital Night Vision？

What is red light night vision?

Can red light really protect your natural night vision?

We do real research and show how red light, IR and night vision actually work together in real-world use this time.

Why CIGMAN Write

We kept seeing lots of conflicting claims on Google about red light and night vision.

What This Blog Solves

This blog helps hunters, campers and night shooters who rely on their eyes after dark.

By Walter Guzman - Nov. 27, 2025

Real-life images captured by thermal and night vision devices.

Table Of Contents

Does red light really protect night vision?

When I search Google for "red night vision" or "red light night vision", half of what I see is flashlight ads and the other half is stories about Vietnam War soldiers seeing demons.

Then I scroll through forum threads and comments. Some people say red light does not damage night vision at all. Some people mix red light with infrared night vision. Others say red light does not affect melatonin, so you can stay up all night under red light and sleep just fine.

Some of this sounds reasonable on the surface. For example, people often mention that darkrooms for film development use red light, and take that as proof that both human eyes and night vision devices are more comfortable with red light.

So I went to literature to check these ideas one by one. I looked at how red light actually interacts with human vision and with night vision gear. Now I feel confident that I can give a clear explanation of the whole "red night vision" topic.

Let’s do a quick red night vision experiment.

2-Minute Red Night Vision Adaptation Test

Step 1: Turn off the room lights and sit in the dark for about 5 minutes.
Step 2: Look at the filter strip below and choose Red, White, or Green.
Step 3: Use the brightness slider to match the preview to how the filter really looks.
Step 4: Press OK to start your 30-second full-screen test.

Pick a filter, then preview it

Brightness (higher = brighter)

Tip: The button colors are based on common red, white, and green night-vision filters, so when you match the brightness in Step 3, you are seeing something close to how real night vision goggles usually look.
In full-screen mode, click anywhere to close the test.

Four controversial claims about red night vision

1 Any red light will not damage your night vision.

2 Red light is the same as infrared night vision, so if you wear red night vision goggles, other people cannot see you.

3 Red light does not affect melatonin, so using red light at night is safe for sleep.

4 Putting a red plastic cover on a white light is basically the same as using a professional red night vision light.

To judge these claims, we need to go back to two basic questions:

1 How does human night vision work?

2 How do we divide light into different bands in physics?

The sections below contain the answers. If you are in rush, you can scroll down directly.

Why do humans have night vision?

If we want to understand how red light affects night vision, we have to start from how night vision is created in the first place.

Here is the short version.

During the day, most of the detail and color you see comes from cone cells.

At night, especially under starlight, weak moonlight, or no natural light, most of what you see comes from rod cells.

Cones vs Rods

A representation of the most important cells in the retina

Image: Jörg Encke, Rods and Cones, CC BY-SA 4.0, via Wikimedia Commons.

Table 1: Cones vs rods: division of labor between the day shift and the night shift

Item	Cones	Rods
Working time	Daytime, bright conditions	Dusk, night, low light conditions
Retinal distribution	Highest density in the central retina, responsible for central vision	Higher density in the peripheral retina, responsible for peripheral vision
Light preference	Need relatively high illuminance to work properly	Respond even under very low illuminance, extremely sensitive
Color	Three types, most sensitive to red or green or blue wavelengths, provide color vision	No color information, only carry light or dark signals
Resolution and detail	High spatial resolution, can see fine text and details	Lower spatial resolution, better at detecting outlines and motion
Night vision	Off duty as the environment gets darker	Main source of night vision ability

Cones sit mainly in the center of the retina. They like bright light, are sensitive to different colors (roughly red, green, and blue), and give you sharp, high resolution, color vision in the daytime.

Rods are more common toward the edges of the retina. They are extremely sensitive to low light, do not carry color information, and are the main reason you can still see shapes in very dark environments.

During the day, your vision is cone driven. At night, especially in very low light, rods take over and your night vision comes from them.

Frog’s skin details visible in total darkness using CIGMAN CNVPRO IR mode 1

Rod cells and dark adaptation

Image: “OpenStax AnatPhys fig.14.16 – Rods and Cones”, OpenStax & UMich Medical School, CC BY, via AnatomyTOOL.

We know that rods are responsible for night vision. Now we need one more concept: dark adaptation.

Dark adaptation means the process that starts when you go from a bright place into a dark place, and your eyes slowly become more and more sensitive to the dark. At first you see almost nothing, then you start to notice shapes, then more detail. This is what people usually mean when they say "my night vision is kicking in".

This sensitivity does not jump up or down. It follows a two stage dark adaptation curve that climbs slowly.

Experiments show that in complete darkness, it takes about 20 to 30 minutes for the eye to reach a stable threshold. Overall sensitivity can increase by roughly three to four orders of magnitude compared with the moment you first entered the dark.

Figure X. Dark adaptation curve (cones and rods). Adapted from Betts et al., Anatomy and Physiology, OpenStax, CC BY 4.0. Access for free at openstax.org.

Image: Figure X. Dark adaptation curve (cones and rods). Adapted from Betts et al., Anatomy and Physiology, OpenStax, CC BY 4.0. Access for free at openstax.org.

In the early part of the curve, cone sensitivity rises a bit and you start to see vague outlines. Later, rods take over, sensitivity climbs much higher, and real night vision appears.

Behind this curve is the chemistry inside the rods. Rods contain a light sensitive pigment called rhodopsin. Strong light quickly bleaches rhodopsin, which means the rods temporarily stop working. Once you go back into the dark, the pigment slowly regenerates. As it comes back, rod sensitivity returns and your vision in the dark improves again.

So the situation where you have been camping for half an hour, your eyes are finally used to the dark, and then someone sweeps a bright flashlight across the group, and suddenly you cannot see anything again, is perfectly normal. Your rods were just bleached again and needed time to recover.

This is also why you often hear that it takes about half an hour to fully adapt to darkness.

What do red light, infrared night vision and red light night vision actually mean?

Using wavelength to separate red light and infrared

From a physics point of view, light is a part of the electromagnetic spectrum. The slice that human eyes can see is called visible light. It runs roughly from 380 to 740 nanometres in wavelength. Different wavelengths appear as different colors. The long wavelength end of that slice looks red.

We usually call the range from about 620 to 750 nm visible red light.

So, if you go beyond roughly 780 nanometres, human eyes usually cannot see that at all. You'd better move into infrared.

Night vision devices mostly use near infrared. The built-in LEDs often have peak output at 850 or 940 nm. To your eyes, this looks like almost nothing, but to a CMOS or CCD sensor it is very bright.

Red light night vision vs. IR night vision

None of these gadgets can make you invisible.

Red light night vision

That simply means using visible red light for illumination. The point is to let you work in the dark while reducing the impact on dark adaptation.

Typical tactics:

1. Red flashlights and red headlamps

2. Red filters on screens

3. Red or amber safelights in darkrooms

IR night vision

This is a different system that sits inside the device, not in your retina.

1. The device employs infrared LEDs of a specific wavelength-usually 850 or 940 nm-to illuminate the scene.

2. The sensor picks up that infrared light and converts it into an electronic signal.

3. This device amplifies and presents it as a grayscale or color image.

Can red light enhance night vision and protect sleep?

A lot of people also say that red light is better for sleep and that using red light at night will not mess up melatonin at all.

Let us look at a very common experience.

It's late at night. And you are very sleepy. You turn off the room light, lie down, and then think: "I will just check my phone for a bit". 5 minutes later, your eyes suddenly feel more awake, and five minutes turn forty. By the time you try to sleep again, your body feels tired, but your brain will not settle down.

What’s happening here is that your eyes have a separate pathway that reports light directly to your internal clock.

This system is especially sensitive to blue and blue-green light, which is exactly the kind of light your bright, cool phone screen emits. So even though your body is tired, that light is telling your brain that it’s still daytime, making you feel more alert and making it harder to fall asleep again.

One of the main jobs of that internal clock is to control melatonin, the hormone that helps you fall asleep. When it gets strong blue-rich light late at night, it delays the rise of melatonin. That pushes back your natural sleepiness, makes it harder to drift off, and can leave your sleep lighter and more fragmented even after you finally do fall asleep.

Red light, on the other hand, has a much weaker impact on this pathway. Deep red has very little power to shut down melatonin, at least at low intensities, compared with blue light. That's why so many people say they feel calmer and sleepier under red or warm light than under bright white LED light at night.

That does not mean that red light has no impact, though. Very bright red light or long exposure can still interfere with your rhythms, and staying up late with any kind of stimulating content will still delay sleep.

So, low-level red light is much kinder to melatonin and to your sleep rhythms than bright blue or white light.

BTW, I actually wouldn’t recommend doing that. In a darker environment, your eyes have to work much harder to gather enough light to see, and over time they end up far more tired than they would be in normal lighting. That extra strain can eventually lead to worse eyesight.

The four claims revisited

1. Any red light will not damage night vision

Not quite. Deep red at low brightness disturbs rods far less than white or blue light. But if the red light is very bright, it will still bleach rhodopsin and reduce dark adaptation.

2. Red light is the same as infrared night vision, so red goggles make you invisible

No. Red is still visible light. People and cameras can see it. True night vision uses near-infrared light plus a sensor, and that part is invisible to the naked eye.

3. Red light does not affect melatonin, so it is safe to stay up with red lights on

Partly true. Low-level red light has a much weaker effect on melatonin than blue light. However, sleep is also affected by how late you stay up, what you are doing, and how mentally stimulated you are. Red light reduces the impact; it does not erase it.

4. A white light with a red plastic cover is basically a professional red night-vision light

Not really. Cheap red plastic usually leaks a lot of shorter-wavelength light. At high brightness, it can still feel harsh and still harms dark adaptation. A real red night-vision light uses deep-red LEDs and is designed to run at very low output.

Step by step guide to using red light for night vision

Once you understand the basic biology and physics, using red light correctly becomes straightforward.

You only need to ask three questions:

01 What kind of red light source is this?

02 Is the brightness higher than it needs to be?

03 Do my habits match the goal of protecting dark adaptation?

Step 1: Identify your red light source

Not all red-looking light is equal. Some are much better for night vision than others.

Table 2: How well does your red light preserve night vision?

Type	Example	NV Rating
IR illuminator for military or digital nods	850nm/940nm IR	Highest
Dedicated red headlamp with low mode	Outdoor headlamp with its own red mode	High
Red menus or overlays on a digital night vision device	On screen display in red or dark theme	Medium
Dedicated red flashlight	Single color red flashlight or tactical red light	High
White light with a real red filter	Headlamp or flashlight with a red filter cap	Medium
Phone screen with red theme or red film	Night mode plus red theme plus red film	Medium
Car tail lights, red camp string lights	Decorative red lights, tail lights	Low
Fake red warm white or amber lights	Some warm white or amber lamps	Low

Step 2: How to check brightness without instruments

Since most people don’t have a lux meter, here are two easy ways to tell if your red light is in a reasonable range.

Method 1: Paper test

In a dark room, shine your red light on a white sheet or a map. Start at the lowest brightness and slowly increase it until you can read comfortably without squinting. Then look up and take in the rest of the room. If the room suddenly feels much darker by comparison, that brightness is still quite high for preserving dark adaptation. Turn it down one step and repeat the process.

Method 2: Distant test

Ask a friend to stand 10–20 meters away from you in the dark and turn on their red light. If you can clearly see the lamp head and can even guess what model it is, the light is too bright.

Ideally, you should see only a soft red glow around your hand, not a sharp bright spot. Old-school tricks like this are often more useful in the field than the lumen numbers on a product page.

Step 3: Three habits that make red light more effective

01 Choose lights that can start in red

Opt for lights or modes that can switch directly into red. Many headlamps use a fixed cycle, such as white high, white medium, white low, then red. In the middle of the night, that means you inevitably flash white high first when you press the button, and your dark adaptation is gone before you even get to red.

02 Use shortcuts that jump straight to red

A better choice is a lamp with a separate red button, or one that lets you long-press to jump straight into red mode. This lets you turn the light on without blasting your eyes with white first.

03 Preset the brightness on night-vision devices

On electronic night-vision devices, it also helps to lower the default brightness and choose dark or red UI themes if the firmware supports it. This keeps the screen from undoing the benefit of using red light in the first place.

References

[1] https://my.clevelandclinic.org/health/body/photoreceptors-rods-and-cones

[2] https://www.aao.org/eye-health/anatomy/cones

[3] "OpenStax AnatPhys fig.14.16 - Rods and Cones - English labels" by OpenStax and Regents of U-M Medical School, UMich MedSchool, license: CC BY. Source: book 'Anatomy and Physiology', https://openstax.org/details/books/anatomy-and-physiology.

[4] Betts, J. Gordon, et al. “14.1 Sensory Perception – Anatomy and Physiology.” OpenStax, OpenStax, openstax.org/books/anatomy-and-physiology/pages/14-1-sensory-perception. Accessed 13 Mar. 2024.