We use both a headlamp and a tail light. The headlamp is a Petzl I've used
extensively for backpacking. It's bright but not nearly so bright as the
blinding high wattage helmet lights used for mountain biking. The beam is
adjustable from narrow to broad focus. The wide beam is useful for general
riding in forests or moonless nights. I believe it disrupts the horse's
night vision the least. The narrow beam is useful for examing trail hazaards
and for riding on the street. The beam angle can also be adjusted to
determine how far ahead the light will shine. I usually point it right at
oncoming automobiles to let drivers know where we are.
The tail light is a red flasher from a bicycle shop. I don't tie it on the
tail anymore because I got tired of the obvious puns and the difficulty of
fastening it. I now hang it from my cantle bag using the light's built-in
bracket. Again, the main purpose of this light is to make us visible to
automobile drivers. The flasher is particularly effective. It does not seem
to bother other horses.
I usually leave the lights off on training rides and do not imagine I would
use them in competition. On the other hand, I think they are essential both
for emergencies and for the inevitable occasions we have to ride on streets
to get to some trails from our house. My wife and I also use the lights to
go on horse "dates" on Friday nights. We ride on the beach or trails to our
favorite hamburger stand in Summerland and return on the roads. It never
hurts to have a little fun with your spouse on horseback to help him or her
tolerate your long conditioning hours in the saddle.