Red Light and Night Vision at Camp

Red light helps because it upsets your dark-adjusted eyes less than white light does. It doesn't make you see better. It just costs you less of what you've already gained.

How long the dark takes

Your eyes adapt slowly. One source puts full adaptation from bright sunlight to complete darkness at approximately 20 to 30 minutes.¹ The two kinds of light-sensing cells recover at different speeds. Cone cells regain their best sensitivity in 9 to 10 minutes of darkness. Rods, the cells for dim light, need 30 to 45 minutes.¹

Age changes it too. Dark adaptation is far quicker and deeper in young people than in the elderly.¹

So a quick flick of a bright headlamp isn't free.

Why red is gentler

Rhodopsin is the pigment in your rods that picks up dim light. It's insensitive to the longer red wavelengths. Red light only slowly depletes the rhodopsin stores in the rods.² Instead, red light is mostly seen by the red-sensitive cone cells.²

That's the reason red is used where people need to read and still see outside. Aviators commonly wear red lensed glasses before taking off in the dark.¹

When it helps at camp

• Looking for something in the vehicle at night, then going back to stargazing.
• Walking to the toilet and back without losing the sky.
• Checking a gauge or a map on a late shift.
• Moving around a shared site when others are asleep or looking at the stars.

When you're cooking or doing a fiddly job, white light is the better tool. Red is for getting around and a quick look.

Setting it up

Many headlamps and lanterns have a red mode. If yours does, learn how to reach it before dark. The manual for your own model will say how.

Keep the red setting low. The point is to light the next step, not the whole site. For what the brightness numbers mean, see the lumens page. Choosing between hand and head lights is a separate question, handled in lantern or headlamp.

What red can't do

It won't speed up adaptation. The 20 to 30 minute figure is for complete darkness, and any light you use will interrupt it.¹

It also isn't a free pass. Red light is still seen, by the red-sensitive cone cells.² It only slowly depletes the pigment in your rods. Slowly isn't never. A bright red lamp held close still costs you something, so keep it dim, point it down and use it briefly, because night eyes are worth guarding.

Children and older campers may differ. Dark adaptation is far quicker and deeper in young people than in the elderly, so an older camper may need longer in the dark before the stars come out.¹ Be patient.