What is “night driving mode” on the rear-view mirror?

Night driving mode on a rear-view mirror is an anti-glare feature that reduces headlight glare from vehicles behind you—either via a manual “day/night” flip tab or an automatic electrochromic (auto-dimming) mirror—so you can see more comfortably and safely after dark. It dims the reflected image to cut harsh brightness without removing your view of the road behind.

What it does and why it matters

At night, bright headlamps in your mirror can cause temporary blindness, eye strain, and slower reaction times. Night driving mode reduces that glare while preserving a usable view of trailing traffic. Most cars achieve this either with a simple mechanical prism in the mirror you flip by hand, or with a powered auto-dimming mirror that adjusts itself in real time.

How manual “day/night” (prismatic) mirrors work

Most basic interior rear-view mirrors use a wedge-shaped (prismatic) piece of glass with a reflective coating on the back surface. In day mode, the mirror is angled so you see the bright reflection from the rear coating. Flip the small lever at the bottom and the prism tilts slightly: the bright reflection is directed upward, away from your eyes, leaving you to see a much dimmer reflection from the front surface of the glass. That front-surface reflectivity is only a few percent, dramatically cutting glare while still showing trailing traffic.

Using a manual day/night mirror

The following points explain how to operate and get the most from a traditional flip-tab mirror.

• Locate the small lever or tab under the mirror housing; this toggles between “day” (bright) and “night” (dim) modes.
• At night, flip the lever toward you (or as marked) to engage the dim setting; flip it back for daytime driving.
• Re-adjust the mirror after flipping if needed so the rear window is centered in view.
• Expect a dimmer, slightly ghosted image in night mode—it’s normal and indicates the front-surface reflection is in use.
• Note that exterior mirrors usually aren’t affected by this lever; they remain unchanged unless your vehicle has auto-dimming side mirrors.

Used correctly, the manual setting quickly reduces glare from following traffic, though you must remember to switch it back for daytime clarity.

How auto-dimming (electrochromic) mirrors work

Auto-dimming mirrors sandwich an electrochromic layer between glass panels. A forward-facing sensor measures ambient light, while a rear-facing sensor detects glare from behind. A small controller applies voltage to darken the mirror proportionally to the glare level. Many systems also link to reverse gear to temporarily undim the mirror for better visibility when backing up, and some vehicles extend the feature to the side mirrors.

Using an auto-dimming mirror

These steps and tips help you verify operation and optimize the mirror’s performance.

• Look for an “AUTO” button or indicator light; ensure the feature is on, especially after valet or service visits.
• At night, cover the rear-facing sensor briefly (usually on the mirror glass or housing) to see if the mirror darkens; uncover to return to normal.
• Expect the mirror to brighten when you shift into reverse—this is by design for better backing visibility.
• Keep both sensors clean; fingerprints, stickers, or dash cams blocking sensors can prevent proper dimming.
• Avoid aftermarket tints, covers, or clip-on accessories on the mirror, which can interfere with sensors or the electrochromic layer.

When powered and unobstructed, auto-dimming mirrors continually adjust to changing lighting, offering set-and-forget glare reduction with minimal driver input.

Benefits and trade-offs

Here are the key advantages of night driving mode along with practical limitations to consider.

• Reduces glare from high-beam and modern LED/laser-style headlights, easing eye strain and fatigue.
• Helps preserve your dark adaptation, supporting quicker recognition of road hazards at night.
• Improves comfort on long drives by minimizing headlight “streaking” and distraction in the mirror.
• Manual mirrors are simple and reliable; auto-dimming adds convenience and proportional control.
• Trade-offs: the image is intentionally darker, so fine detail may be less visible; auto-dimming requires power and can fail if sensors or circuits are compromised.

Overall, the benefits outweigh the compromises for most drivers, especially in dense traffic where headlight glare is frequent.

Care, troubleshooting, and when to seek service

If your night mode doesn’t seem to work as expected, the following checks can help resolve common issues.

1. Clean the mirror glass and the small sensor windows with a soft, non-ammonia glass cleaner and microfiber cloth.
2. For manual mirrors, verify the lever fully clicks into each position and re-aim the mirror after switching modes.
3. For auto-dimming, confirm the AUTO function is enabled and nothing blocks the forward or rear sensors.
4. Test at dusk or in a dark garage with a flashlight aimed at the mirror to simulate glare.
5. Check the relevant fuse or power supply if the mirror includes additional features (compass, HomeLink) that also seem inoperative.
6. Look for signs of electrochromic failure (permanent dark blotches, bubbles, or leaks); if present, replacement is usually required.
7. Consult the owner’s manual for model-specific sensor locations and settings; seek professional service if problems persist.

Regular cleaning and correct setup solve most issues; hardware faults or fluid leaks in auto-dimming mirrors typically call for mirror replacement.

Frequently asked clarifications

Is night driving mode the same as mirror defrost?

No. Defrost or heating elements clear fog or ice, typically on exterior mirrors. Night mode reduces glare; it doesn’t warm the glass.

Do side mirrors have night driving mode?

Some vehicles include auto-dimming side mirrors that work with the interior mirror. Manual flip-style dimming is generally only on the interior rear-view mirror.

Summary

Night driving mode is an anti-glare feature for interior rear-view mirrors. Manual versions use a prism you flip to route away the bright reflection, leaving a much dimmer image; auto-dimming versions use sensors and an electrochromic layer to adjust tint automatically. Both approaches reduce headlight glare, helping you see more comfortably and safely after dark.

How to use a day-night rear view mirror?

Sometimes it’s called a prismatic mirror, which just means your mirror has the option to switch between day and night modes. Just push it down to switch into night mode, and pull the tab back up when it’s daylight.

What are day and night settings for rearview mirrors used for?

Day and night IRVM is a type of rearview mirror used in vehicles. It is an anti-glare car feature that enables drivers to view the back part of the car during daytime and nighttime. The mirror features unique designs that ease its adjustment to different angles. This helps accommodate different lighting conditions.

How does night mode work on a rear view mirror?

Coating. Since the glass reflects only a small portion of the light it dims the reflection of the headlights. Behind you significantly reducing the glare.

What should you use on your rearview mirror at night?

At night, use the night setting (or anti-glare or day-night) on your rearview mirror by flipping the small tab at the bottom of the mirror to reduce glare from headlights. This adjustment changes the angle of the mirror, allowing light to reflect off a less reflective front surface of the glass instead of the more reflective back coating, significantly dimming the reflection of following headlights.
 
How to Activate the Night Setting

1. Locate the tab: Find the small tab or lever at the bottom of your rearview mirror. 
2. Flip the tab: Pull the tab towards you or push it away from you. The direction depends on the specific mirror, but it shifts the mirror’s position. 
3. Confirm the change: You will still have a view of the road behind you, but the bright headlights from following cars will be much dimmer. 

Why It Works

• Daytime Mode: Opens in new tabThe mirror is positioned to reflect light off a highly reflective surface on the back, giving a bright, clear view. 
• Nighttime Mode: Opens in new tabThe tab flips the mirror to use the slightly less reflective front surface of the glass, diffusing the bright headlights and reducing glare.