Maybe you're sensitive to "things that go bump in the night". I was when I was younger, but now that I'm much older, I'm not, probably because I'll be joining the spirits in a few years. Maybe when regressing, you're triggering past feeling from when you were little, in which case there may be nothing you can do about it other than not to regress.
There are other ways to think about it though. You know your house or apartment. In the dark, you have the edge, not an intruder. Of course if it's something spiritual, it would not be hindered by the dark. I like horror movies and the dark, so I'm weird I guess. As you probably know, I write scary stories, so that's where I live. Sometimes you just have to embrace your fears. When I was a kid I was terrified by the dark, but I've learned to embrace my fears and enjoy them. But I'm no longer visited by those fears or the things that go bump.