This is especially true after running for several hours at night. It can get to you! Before the Pinhoti 100 in November of 2008, I did my first night run. I ran at Oak Mountain State Park, starting about 3 hours before dark and continuing until almost midnight. I was running on trails I knew very well but it was a very strange feeling to be out in the woods alone, running. I had purchased a very bright headlamp. It was similar to the Fenix HP20 but an older model. It had a battery pak that was either worn on the head strap or on a belt and it's maximum output was 200 lumens.
This headlamp had two problems. One was it would not stay in place. The battery pack was too heavy and moved around. I kept trying to adjust it but it was never comfortable. Another more serious problem was that it was far too bright for running in the woods. It might work fine on a long open road but not in a dense forest. Every time I looked off the trail the beam would hit a branch or leaf and the reflection was so bright I was momentarily blinded. I set the headlamp to a lower setting, about 70 lumens, and that worked fine. I realized there is no reason to wear a bulky, heavy and expensive headlamp when most of the Petzl and Black Diamond headlamps that sell for $30 to $50 produce plenty of light. And they are "light."
I do not like running with just one light source, especially just a headlamp. There are two very good reasons to always have two lights. First, you are depending on one light and it breaks or the battery go dead, you may be in big trouble. Second, because the headlamp is located almost exactly in you line of sight, it creates no visible shadows. This makes it hard to see rocks and roots and almost impossible to see shallow dips or holes in the trail. I did run my first 100 mile run with just a headlamp but not intentionally. I accidentally left my flashlight at the aid station on top of Mt Cheaha during the Pinhoti 100. I was carrying it as a backup only so I was not too concerned. I had extra batteries in a later aid station just in case.
Before running The Leadville 100 in 2009 I tried running with a flashlight and a headlamp. This makes it much easier to see what you are about to step on. I now use a Fenix LED flashlight that sells for about $59 and a Black Diamond headlamp that was less than $40. Each has several brightness settings up to about 70 or 75 lumens plus the flashlight has a super bright beam for emergencies. I use the headlamp to look down the trail 10 to 20 yards and flashlight to light the trail just in front of me. If I see difficult terrain in the headlamp beam up ahead, I follow it until it is close and pick it up in the flashlight beam. This takes a little practice and it does require concentration.
This year at Wasatch I was running with trekking poles so I could not use a flashlight. I had seen adds for a light that is attached to a vest, but I would be running with my Nathan Hydration Pack which would interfere with the light. I read about the SureFire Saint Minimus LED Headlamp and decided to try one. It was a bit expensive at $140 but I liked it. I wear it around my waste, not on my head. It is a "floodlight" not a "spotlight" (most headlamps are spotlights) so it lights up the area just a few feet in front of me. It has an infinite light setting from 0 to 100 lumens which I also like. The one bad thing is it requires a CR123A lithium battery so by two or three and take them with you. They are harder to find than AA and AAA batteries used by the other lamps I talked about.
A few personal notes on night running.
I love to run over night. I never get sleepy, even in the early morning hours. It is a truly amazing experience. My first night run, that I discussed above, was three months before Pinhoti August. The woods were full of fireflies. As I ran through the woods I would see a glimpse of light to one side or the other. Of course, when I turned my head to look, the beam would overwhelm the dim light from the firefly. I finally stopped and turned the headlamp off to watch. I did this several times. I also found out the the trails in the State Park close at dark. The park police were not happy with my night run and suggested I not do it again.
My favorite memory from Leadville (other than the finish line) was running up the "Powerline" climb 20 miles from the finish in the early hours of the morning. After a couple of miles of steep climbing straight up the hill I hit a traverse to the left. As I started across the traverse, I looked down. Below me was a line of 15 or 20 headlamps coming up Powerline in the dark in one long line. Later, after going over Sugarloaf Pass and heading down toward Turquoise Lake, it was beginning to get light and I could just make out the lake. I could again see the headlamps of runners, this time heading along the far shore of the lake just 8 or 10 miles from the finish. I just wished I had a camera with me. I was also a little envious of them. I had about 15 miles to go.
At Wasatch this year I reached the Desolation Lake aid station in the early morning hours. It was very cold and everything was covered in frost. The aid station volunteers had a large and very tempting bonfire burning. RULE: Stay away from warm fires in the middle of a cold night, they are dangerous. (There are some really dedicated aid station workers in all 100 mile runs, but especially in the mountain run.) Next came a 1000 foot climb to the north ridge of Peak 9990 at the Canyons Ski Resort. That fire was visible all the way up. At the crest of the ridge and at several spots along the ridge you could see Kimble Junction or Park City to the left and the Salt Lake City valley floor to the right. Truly a spectacular sight I will never forget.