屏幕时间影响计算器 — 公式

## Screen Time Health Impact

### Impact Scoring

- Each hour of screen time adds 5 points
- Screen use before bed adds up to 15 points for sleep disruption

### The 20-20-20 Rule

Every 20 minutes, look at something 20 feet away for 20 seconds to reduce eye strain.

### Guidelines

| Score | Impact |
|---|---|
| 0-30 | Low impact |
| 31-55 | Moderate (use 20-20-20 rule) |
| 56-75 | High (consider reducing) |
| 76+ | Very high (take action) |