Every night · 4 minute read
How your eyes adapt to the dark
It takes twenty to thirty minutes to see the faintest stars, and one glance at a white screen to lose them.
Two kinds of cell
Your eye has cones, which see colour and need plenty of light, and rods, which see only in shades of grey but are far more sensitive. In the dark the cones give up within a few minutes and the rods slowly take over.
Why red light
Rods are almost blind to deep red light. A dim red torch lets you read a chart or find your feet without resetting the slow work your rods have done. That is why the whole of our site can switch to red, and why we ask everyone on the deck to use red torches only.
Making the most of it
- Give yourself twenty minutes away from lights before looking for faint things.
- Put phones into red mode or away entirely. One white screen undoes the wait.
- Look slightly to one side of a faint object: the edge of your vision is richer in rods.
- Breathe slowly and blink. Tired, held-open eyes see less.
