Asharksrevenge has good advice, I think.
I think if you were training for something like the olympics it probably matters a lot, a lot. But if you're training for life, like I am, I think getting it in is the number one most important thing. It must be a priority. For me, that must happen first thing in the morning, which is unfortunately 5:30.
If it doesn't happen then, it might not happen.
But heck...I always say no one can mess with my 5:30 workout because there is nothing going on at 5:30 in the morning. Well...who can mess with your midnight workout? Again, nothing going on!