It’s called Fall with good reason.
Less daylight means more night riding. Add leaf covered, wet, slippery roots and rocks, and you have the increased potential for Falling.
But darkness makes me ride better. Not being able to see as well means that I can’t get picky with lines to take. It forces me to keep my body relaxed and moving forward.
If I ride a trail at night, and then ride that same trail during the day, I feel like I’m riding faster. Being alone in the woods, with an 8+ year-old light system and hearing Blair Witch noises also makes me ride faster.