How to See in the Dark: Rods, Cones and Night Hiking
I have a couple of trickster cousins who think it's hilarious to switch off their headlights while driving in the dark. Hiking at night doesn't plunge you quite as terrifyingly into pitch blackness, but even experienced hikers can feel uneasy and off-balance in the woods at night.
Loss of visual acuity heightens all the other senses. Snapping twigs sound strangely magnified. The forest's pine scent develops rich, earthy undertones. Reflective surfaces -- rock faces, dunes and lakes -- loom unexpectedly out of the blackness. Heightened awareness is one of the things advocates love about night hiking. However, those who find themselves hiking in the dark unexpectedly say the experience can be terrifying. Santa Fe attorney and avid hiker Debbie Ramirez found herself on a night hike after misjudging the time it would take to descend from Mount Whitney. She said, "I could see the trail, barely, but I had no idea what was lurking in the woods. It was pretty scary."
The human retina is made up of rods (which help us see in the dark) and cones (which are concentrated in the center of the pupil and work best in bright light.) Understanding how rods and cones differ is the trick to being able to see in the dark [source: American Optometric Association]:
- Cones: Thanks to all those centrally-concentrated cones, most of us have a middle-vision blind spot in low-light conditions. To compensate when hiking at night, focus your eyes slightly to one side of objects you want to see.
- Rods: It takes rods a full 30 to 45 minutes to adapt to low-light conditions. Before setting out on your night hike, first find a dark spot and sit for a half-hour. Once your eyes adjust, you'll be amazed at how well you'll be able to see in the dark.
Learning how to see in the dark is essential to staying safe on a night hike. But what about those creatures Debbie Ramirez felt lurking in the woods? Is it really safe to hike at night?