Display & Light Guide
Real-time brightness, color temperature, and ergonomic suggestions based on your current local time. No sensors needed — just your browser telling you what your eyes need. Perfect for long meeting days and back-to-back video calls.
Your current settings
The Display Guide shows five data points. Here's what each one means and how to act on it:
| Metric | What it means | How to act |
|---|---|---|
| Period | The time-of-day category based on your local time. Your eyes' sensitivity changes throughout the day — this tells you which phase you're in. | Use this as a general awareness check. If you're in "Late Night," consider if the work can wait. |
| Color Temperature | Measured in Kelvin (K). Lower numbers = warmer (more orange/red), Higher = cooler (more blue). Warm light in the evening helps melatonin production. | On macOS: System Settings → Displays → Night Shift. On Windows: Settings → System → Display → Night light settings. |
| Brightness | Percentage of maximum brightness. Your ambient light sensor adjusts this automatically, but it doesn't know what time it is — manual override is often better. | Use your keyboard brightness keys (F1/F2 on most laptops) or the slider in Quick Settings / Control Center. |
| Tip | Actionable advice specific to your current time period. Includes the 20-20-20 rule reminder and blue light warnings. | Set a timer for the 20-20-20 rule. Many apps (like Time Out, EyeLeo) can do this automatically. |
| Posture | Ergonomic reminder based on the time of day and likely meeting fatigue level. Your posture tends to degrade as the day goes on. | Stand up and stretch between meetings. Consider a standing desk or a posture reminder app. |
Your display settings should change throughout the day to match your eyes' natural sensitivity. Here's the full reference table:
| Local Time | Color Temp | Brightness | Why | Ergonomic Tip |
|---|---|---|---|---|
| 06:00–10:00 | Neutral (5000K) | 70% | Morning adaptation — your eyes are transitioning from darkness to light | Ease into the day. Don't jump into max brightness. Your pupils are still dilated from sleep. |
| 10:00–18:00 | Cool (6500K) | 100% | Peak visual acuity — your eyes are most sensitive and adaptable | Full brightness is appropriate, but follow the 20-20-20 rule: every 20 minutes, look 20 feet away for 20 seconds |
| 18:00–22:00 | Warm (3500K) | 50% | Wind-down phase — blue light at this time can delay sleep onset by 10–30 minutes | Enable Night Shift (macOS) or Night Light (Windows). If you're still in meetings, keep them under 45 minutes. |
| 22:00–06:00 | Warm / Red Shift | 30% or lower | Recovery phase — your body is preparing for sleep | Consider if this meeting can be async. Use f.lux or Night Shift at maximum warmth if you must work. |
Different monitors have different brightness capabilities. A 50% brightness on a MacBook Pro (500 nits) is much brighter than 50% on a typical office external monitor (250–300 nits). Here's how to adjust the guide for your setup:
| Monitor type | Typical max brightness | 50% feels like | Recommended for |
|---|---|---|---|
| MacBook / MacBook Pro | 500–1600 nits | Very bright | All-purpose, but consider reducing in the evening |
| Windows Laptop | 250–400 nits | Moderate | Office use, co-working spaces |
| External Monitor | 250–350 nits | Moderate-low | Home office, dedicated workspace |
If you use an external monitor with a MacBook in clamshell mode, select "External Monitor" — MacBooks in clamshell mode often run brighter than when open.
Scenario: It's 22:30 in Tokyo and you're deciding whether to join a late meeting with your US-based team.
Click below to simulate this scenario:
Expected output: The guide will show Late Night period with a warning that it's past 10pm. The recommendation: consider async communication instead of a live meeting. If the meeting is urgent, keep it under 30 minutes and use maximum warmth settings on your display.
- Open the page — Your browser automatically detects your timezone and current local time. No permission needed, no data sent to any server.
- (Optional) Select monitor type — Choose your display type for more tailored brightness suggestions. MacBooks, Windows laptops, and external monitors have different typical brightness ranges.
- Read your personalized suggestions — Five data points: the time period, recommended color temperature, brightness percentage, an actionable tip, and a posture reminder.
- Take action — Manually adjust your display settings based on the suggestions. Enable Night Shift / Night Light if recommended.
Example: If it's 20:30 your time, you'll see "Evening (18:00–22:00)" with warm color temp (3500K), 50% brightness, and a tip to reduce blue light.
Why this matters: The average remote worker spends 10+ hours per day looking at screens. Proper display settings can reduce eye strain by up to 40%, improve focus duration by 25%, and help maintain healthy sleep patterns.
Disclaimer: These are general ergonomic guidelines based on time-of-day lighting principles. They are not medical advice. Consult an eye care professional for personalized recommendations.
Intl.DateTimeFormat().resolvedOptions().timeZone — the same standard API used by virtually all modern web applications, including Google Calendar, Zoom, and Slack. If your device's system time and timezone settings are correct, the detection will be accurate. The guide doesn't check your timezone again after page load; it continuously monitors the local time.