Your display, in sync with the sun
CircadianShield tracks the sun's real position and smoothly adjusts your screen's color temperature from 6500K daylight to 1800K candlelight — protecting your sleep, focus, and long-term health.
Blue light at night disrupts your sleep
Your display emits peak blue light at 450 nm — the exact wavelength that suppresses melatonin and confuses your body clock.
Delayed Sleep Onset
Evening blue light shifts your melatonin release by 1.5–3 hours, making it harder to fall asleep even when you feel tired.
Daytime Fatigue
Poor sleep quality compounds. Fragmented circadian signaling leaves you groggy, unfocused, and reaching for caffeine.
Eye Strain & Headaches
PWM flicker from display dimming and harsh blue wavelengths contribute to digital eye strain, especially at night.
Three steps to healthier light
CircadianShield runs quietly in your menu bar and adapts your display automatically.
Install
Download CircadianShield and drag it to your Applications folder. No account required.
Set Your Location
Choose from 130+ city presets or let CircadianShield auto-detect your coordinates for precise solar tracking.
It Just Works
Your display color temperature adjusts automatically as the sun moves. Warm at night, bright in the morning.
Everything your eyes need
Built on real circadian science, not just a color tint slider.
Solar-Based Filtering
Tracks your sun's real elevation through 11 twilight phases with smooth sigmoid transitions between 1800K and 6500K.
Morning Boost
A 6500K wake-up boost synced to civil dawn helps suppress residual melatonin and jumpstart your alertness.
20-20-20 Break Timer
Every 20 minutes, look at something 20 feet away for 20 seconds. Smart pause during video calls and full-screen apps.
Circadian Health Score
An A–F grade based on your light exposure patterns and timing. Track your light debt and improvement over time.
Per-App Profiles
Color-accurate mode for Photoshop, cinema mode for Netflix, coding mode for Xcode. Each app gets the right filter.
PWM Flicker Protection
Software dimming overlay eliminates the invisible flicker from hardware PWM backlight dimming that causes headaches.
Built on melanopic EDI & CIE S 026
CircadianShield uses the CIE S 026:2018 standard to calculate melanopic equivalent daylight illuminance — the metric that actually predicts circadian impact. Not just "blue light filtering."
Read the Science