Yellowstone Prong, Graveyard Fields, NC - 2013
(Click on photo to enlarge.)
Arriving early solves two problems. First of all, the turistas with their mini-vans full of kids usually don't show up before 10 am or so. The scene above is only a couple of hundred yards off the highway, and would be crawling with kids playing in the water around mid-day. By going early you can avoid the crowds and the noise. It's not that I hate kids, I just don't want them in my nature photos.
Another advantage to going early is that the light is better. Later in the morning this area would be flooded with direct sunlight, creating too much contrast for good pictures. The white water of falls or rapids blows out too easily in direct sunlight, robbing the scene of any detail in the stream. In the early morning, while the light is still soft and indirect, it's much easier to retain detail in both the shadow and highlight areas.
I'm naturally an "early bird", so getting on the road while it's still dark is no problem for me. A cup of hot coffee, and I'm ready to go! For others it may be a struggle, but the rewards for hikers and photographers is well worth it. You'll get better photos, and I think you'll enjoy the solitude you'll find when you've got the trail all to yourself!