It is my personal belief that seahorses prefer low lighting, though I have gotten slammed down for that belief, being reminded that seahorses are also found in shallows where "the sun is very bright". I guess we know I think that's whooey. I know they do live in shallows, but that's a bit different than our aquariums...just my opinion.
They have very good eyesight (think about their hunting abilities and the prey they hunt) and I don't believe they need the lighting to be at high levels. I also know that my own girls were very active when the lunars were on. This is when the pods are active, also.
Again, just my opinion.