I'm a man who rides in the inner city day and night. I have about the same problems with bad people regardless of ambient light levels. That is to say, infrequent minor problems. Teenage boys sometimes rush me while yelling, "I want your bike!" I don't think they are really trying to take my bike. Unless they are stupid (a distinct possibility), they must know that they would also be injured if I fell on top of them at a good speed.
One thing--I am very careful about which stores and restaurants I will stop at. There are many parking lots where crackheads and the like congregate. They are likely to go after your bike, even if they could get only four or five dollars or a rock for it. Not to mention your wallet.
If you are not big or strong--try to talk your way out of trouble before fighting or running. I think a u-lock is a better weapon than pepper spray. Crackheads can take a lot of pepper but only so much case-hardened steel.
But basically I think all of this advice is a waste of time because you are unlikely to get in trouble, and all trouble is different, anyway. So just be aware and alert, and have a good time cruising the dark streets!