By David Henry,
CTS Ultrarunning Coach
Sooner or later every ultrarunner has to get comfortable running at night. While running at night is still just running, seeing well on a trail can be a challenge unless you address a few key difficulties that crop up in the dark. We’ll tackle each one individually below.
If you’ve ever shopped for headlamps you’ve probably run across the term “lumens” before. Lumens are a measure total quantity of visible light that is emitted by the light. It used to be that getting a headlamp with greater lumen output required either a lot of weight or a lot of money. These days, you can get a decent light with 100-300 lumens that will both be lightweight and have good battery life without being super expensive. There are also models that have adaptive lighting that will brighten if you’re looking far away or dim when you’re looking close or at something reflective like snow. This feature helps conserve battery life and also helps you use the appropriate amount of light for the situation. Blasting a bright light at an object in your hands makes it difficult for your eyes to adjust once you look far down the trail again.
Our perception of depth is something we take for granted during the day, but at night it can nearly disappear, particularly with a headlamp that is shining light at the same angle as our eyes. This is especially true with objects that are the same color as the trail, like rocks, roots and just uneven dirt. A brighter light with more lumens can be helpful, as well as a lamp with a wider more dispersed beam shape, but too much light can be problematic. A super-bright light can wash out terrain features and make rocks and uneven soil blend together, ironically making it harder to see the holes and obstacles you’re trying to avoid. Very bright and concentrated lights are also more likely to lead to tunnel vision, where the differential between what’s in the beam of light and outside of it is so great that everything outside the beam essentially disappears. Without context from the periphery, you can get disoriented.
Instead of just adding more lumens, the best remedies are to add a second light either on the waist or in the hand, or just use a waist or hand light to start with. Using a light that’s not attached to your head creates variation in the shadows that are cast and dramatically improves your depth perception.
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The color of the light or lens can also influence the effectiveness of your lights. You want to create some contrast with the color of the light and the color of the terrain. If you’re running in terrain that has a lot of light brown gravel, you may find a cold white/blue light helps you see more clearly than a warmer yellowish light. If you’re running somewhere with light sandy terrain or whitish limestone, that cold white/blue light may less ideal.
Backups and Spares
I almost always carry a backup or spare light. While you can take extra batteries as well, I tend to just opt for an extra light for complete redundancy. While less common than just draining the battery, bulbs do burn out or the electronics go haywire and even with fresh batteries you still will be without light. Granted, in a race you can hope to tag along with someone who was more lucky or better prepared, but that should be your last resort. My personal preference is to have a trusty headlamp as my primary and also have a hand flashlight in my pack, specifically one that also functions as a USB charger. You may not need the USB charger during short nighttime training runs, but for races longer than 15 hours I use one to charge my GPS watch mid run for navigation and to get a full data track for the race. Currently, no watch on the market will record 15+ hours unless you reduce the recording interval and turn off wrist heart rate monitors. I also always put an extra headlamp in drop bags that will be at aid stations during the night, just in case I need to also swap the lamp.
To sum it up, more light is better, but look for best compromise with weight, price, and color. Work the angles with multiple lights, either with another person or on your own body. Lastly, have even more lights for backups. While it’s been done, running through the dark with your phone flashlight, running with someone else who has a light, and running with no light at all are not fun options in training and are likely to significantly slow you down in a race. Don’t be that runner!