I have some Japanese maples I have to bring in at night (for security
reasons). I have several strong spotlight growlights I put them under for
several hours at night. I was wondering if there's a problem with leaving the
grow lights on them all night.

I wouldn't do it. Some annuals are grown with 24 hours of light, but most
plants need at least some sleep. There are certain hormones that are rearranged
in the dark. I trust you are giving them a solidly cold dormant period during
the winter.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)