20-20-20 Rule Timer
The 20-20-20 rule is the most widely recommended guideline for reducing digital eye strain and preventing postural fatigue at a computer. Every 20 minutes, look at a point roughly 20 feet (6 metres) away for 20 seconds. This relaxes the ciliary muscles in your eyes (which hold the lens in the contracted shape needed for close focus) and prompts a postural reset.
How it works
Your eyes have a focusing muscle (the ciliary muscle) that contracts to hold your lens in a curved shape for close-up vision. Sustained close focus for hours causes this muscle to fatigue — the result is tired, dry, blurry, or achy eyes. Looking far away relaxes the ciliary muscle completely. Twenty feet (6 m) is the clinical threshold at which the eye is in its fully relaxed "distance" state. Twenty seconds is enough time to get a meaningful relaxation effect.
POSTURE TIP
Use the 20-second break to also reset your posture: sit tall, roll your shoulders back, take a slow breath, and check that your head is over your shoulders rather than in front of them. The timer is the cue; the posture check is the habit.
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GET UNHUNCH — $14.99FAQ
- What counts as 20 feet away?
- Anything roughly 6 metres from your face. Out a window is ideal. If your room isn't that large, the far wall works — the key is that your eyes are fully relaxed from close focus.
- Can I just close my eyes for 20 seconds instead?
- Closing your eyes does provide rest, but doesn't fully relax the ciliary muscle the same way distance vision does. Looking at a far point is the more effective intervention for eye strain specifically.
QUELLEN
- Rosenfield M (2011). Computer vision syndrome: a review of ocular causes and potential treatments. Ophthalmic & Physiological Optics, 31(5):502–515.
- Owen N, Healy GN, Matthews CE, Dunstan DW (2010). Too much sitting: the population-health science of sedentary behavior. Exercise and Sport Sciences Reviews, 38(3):105–113.