I just wanted to mention as a sidenote; my teacher used to tell me to play in the dark (in a spooky voice), he's a character. However I found practicing in the dark some of the time very useful IMO, because knowing the instrument is key, no pun intended because of what was said about knowing keys as well. Your bass may have some natural landmarks also if it's a vintage instrument maybe. I have no idea what you go through, Dave, on a daily basis but I commend you, you'll be good no matter what age you are becasue you have the drive. Fred