How to read your Blue Light Impact Score

Your Blue Light Impact Score is a 0–100 estimate of how likely your evening light exposure from screens is to interfere with your natural sleep signals. It combines timing (how close to bedtime), dose (minutes + brightness), and mitigation (filters, glasses, room lighting, distance) into one number you can improve.

• 0–24 (Low): Minimal disruption. Your screen habits are unlikely to meaningfully delay sleep for most people.
• 25–49 (Moderate): Some disruption. You might notice slightly longer time to fall asleep or lighter sleep.
• 50–74 (High): Strong disruption risk. Night screens may noticeably delay sleep onset and reduce sleep quality.
• 75–100 (Very High): Big disruption. You’re in the “doomscroll danger zone” where changes can make a huge difference fast.

• Take a screenshot and re-run after changing one habit (brightness, filter, or screen cutoff) to see the impact.
• If your score is high, start with the highest-leverage fixes: stop screens earlier and use stronger filtering.
• Use the score as a trend tool: compare week to week, not “one-night perfection.”
• Share it in group chats as a challenge: “Who can get their score under 30 tonight?”

Frequently Asked Questions

• What is “blue light” and why does it matter at night?

  Blue light is the short-wavelength part of visible light that your eyes and brain often interpret as “daytime.” In the evening, lots of bright, blue‑heavy light can nudge your circadian clock later and reduce melatonin signaling—making it easier to stay awake and harder to fall asleep.

• Is this calculator scientifically exact?

  No—this is an educational estimate. Real effects depend on your sensitivity, the exact spectrum and brightness of your devices, your room lighting, and your overall sleep routine. Use the score to compare habits and find improvements.

• Do Night Shift / blue filters actually help?

  They can help by shifting your screen toward warmer colors and reducing blue-heavy light. They don’t replace the two biggest levers: less screen time and earlier cutoffs.

• Are blue‑light blocking glasses worth it?

  They may reduce blue light reaching your eyes—especially stronger amber lenses. For some people, they’re a useful “insurance policy” when screens are unavoidable. For others, comfort and consistency matter more than the tech. Try and re-test your score.

• What if my score is high but I fall asleep fine?

  You might be less sensitive—or other factors (sleep pressure, exercise, schedule) may be doing the heavy lifting. Still, high night light exposure can show up as lighter sleep, later wake time, or groggier mornings over time.

How the Blue Light Impact Score is calculated

The goal of this calculator is simple: translate your evening screen routine into one score that is easy to understand and easy to improve. In real life, researchers measure light exposure with calibrated sensors and account for the exact spectrum (how “blue-heavy” the light is), the angle of light entering your eyes, pupil size, time of day, and individual sensitivity. You don’t have that in a quick web tool—so we use a practical approximation that still reflects the biggest levers you can control.

The score is built from five parts: timing, duration, intensity, mitigation, and context. Each part contributes points, then the total is capped to 0–100.

The most important factor is screen cutoff—when you stop using screens relative to when you try to sleep. Light exposure right before bed tends to have a bigger impact than the same exposure earlier in the evening. We compute the minutes between your “last screen time ends” and your bedtime. The closer that gap is to zero, the more points are added.

• 0–15 minutes: large timing penalty
• 15–45 minutes: medium timing penalty
• 45–90 minutes: smaller penalty
• 90+ minutes: minimal timing penalty

Next is how long you’re exposed. Two hours of screens in the evening usually produces a higher “dose” than twenty minutes. We treat your reported minutes after sunset as the base exposure and scale it with diminishing returns: going from 0 to 60 minutes matters more than going from 240 to 300 minutes.

Brightness matters because more luminous output generally increases the light reaching your eyes. Distance matters because light intensity drops rapidly as you move farther away (in everyday terms: holding a phone 20 cm from your face is very different than watching a TV across the room).

In the calculator, brightness is a simple multiplier (low/medium/high). Distance reduces impact when you’re farther away and increases impact when the screen is very close. This is why a dim, warm laptop across the desk can score lower than a bright phone inches from your face.

Night Shift / blue filters shift the screen toward warmer colors and reduce blue-heavy output. Blue‑light glasses may reduce the blue component reaching your eyes (especially amber lenses). Both are treated as “mitigation multipliers” that reduce the intensity component of the score.

Important nuance: filters and glasses do not make a 2‑hour scroll session “free.” They help, but the highest-leverage change is still shorter and earlier screen use.

Content type matters because it changes both arousal and how you use the device. Fast‑paced video and gaming can keep your brain “up,” while reading is typically calmer. Room lighting matters because a bright room reduces contrast between the screen and your surroundings, often making the screen feel less intense. A pitch‑dark room can make a screen feel glaring and more stimulating.

Bottom line: this isn’t a lab device. It’s a practical score that tends to move in the right direction when you make the right changes.

What the results mean (melatonin + sleep latency)

The calculator outputs three things: (1) a 0–100 impact score, (2) an estimated melatonin suppression range, and (3) an estimated sleep latency increase. These extra numbers are included because people often ask, “Okay, but what does 62 mean for my night?”

Melatonin suppression in this tool is expressed as a broad range (for example, 10–25%). That’s intentional. Individual sensitivity varies a lot: two people can have the same screen habits and experience different outcomes. Also, device brightness is not standardized across phones, tablets, monitors, and TVs. Treat the percentage as a “directional” indicator, not a medical measurement.

Sleep latency is the time it takes to fall asleep after you try. Many people experience longer sleep latency when they combine light exposure with stimulating content or stress. The calculator estimates an “added minutes” value. If the estimate says +15 minutes, it means your routine could be nudging your fall‑asleep time later by roughly that amount.

There are two common mechanisms. First, bright blue‑heavy light in the evening can reduce the “night signal” your brain expects, so you stay alert longer. Second, scrolling and gaming can be emotionally activating: novelty, social comparison, notifications, and problem‑solving all keep the mind engaged. That’s why “same brightness, different content” can feel totally different.

• Stop screens earlier: aim for a 45–90 minute buffer before bed when possible.
• Lower brightness: especially in the last hour.
• Turn on strong Night Shift / warm filter: make the screen look noticeably amber.
• Add room light: a warm lamp can reduce screen contrast (avoid harsh white overhead lighting).
• Move the screen farther: even 10–20 cm more can help on phones.

If you want a “minimal friction” plan: keep your routine the same, but set a strong warm filter to turn on automatically, drop brightness to low after dinner, and move your phone farther away (or use a larger screen farther away) for the last 30 minutes.

Realistic examples (so you can sanity‑check your result)

Below are a few example inputs and what typically happens to the score. Your exact number may differ, but these examples help you understand the direction of change.

Bedtime: 11:00 PM. Screen ends: 10:55 PM. Minutes after sunset: 90. Brightness: high. Filter: off. Glasses: no. Distance: 25 cm. Content: video. Room: dark.
Typical outcome: Very high score. This is peak “light + timing + proximity.” The biggest win is stopping earlier or watching farther away with strong filtering.

Bedtime: 11:00 PM. Screen ends: 10:15 PM. Minutes after sunset: 60. Brightness: low. Filter: strong. Glasses: no. Distance: 45 cm. Content: reading. Room: dim.
Typical outcome: Low to moderate score. You still use screens, but the timing buffer and mitigation keep the impact down.

Bedtime: 12:00 AM. Screen ends: 11:50 PM. Minutes after sunset: 180. Brightness: medium. Filter: some. Glasses: yes. Distance: 30 cm. Content: social. Room: dark.
Typical outcome: High score. Glasses help, but the routine is still very close to bedtime with lots of exposure. The best fix is cutting off earlier or switching the last 30–60 minutes to a non-screen wind‑down.

Bedtime: 10:30 PM. Screen ends: 9:45 PM. Minutes after sunset: 90. Brightness: medium. Filter: none. Glasses: no. Distance: 250 cm (TV). Content: video. Room: dim.
Typical outcome: Moderate score. The screen is brighter than you think, but the distance and earlier cutoff usually reduce the overall impact compared to a phone in bed.

Want to make this viral? Post your score, then post your “after” score from one change. The before/after story is the shareable hook.