Is it normal for concentration practice to have negative effects?

For me it seems to decrease the amount of awareness that I have. I'm more prone to walking into things, having blind-spots. It's like a part of my brain shuts down, the part that would normally make me aware of things.

I do one-point focus, usually on a small dot.

I don't get this negative effect when I just do mindfulness of anything.

My experience is that it isn't a matter of being normal or not, more that the intense inward focus of concentration practice sometimes bleeds outward into everyday life and I lose track of what's going on. I've had this kind of thing happen. This hasn't typically happened for me with mindfulness practice. There I become more aware of what's going on outside, if I'm tracking outside sensations.

Actually, there are some even more negative effects of concentration practice. If you want to find out more, check the Books Discussion forum. I recently published an ebook memoir where I talk about this.

yes, these are totally normal for me. I even get a little stumbley while doing walking meditation. I always considered it just was what it was without applying...negative to it. Creating a feedback loop tends to get the mind concentrated...on the one thing....it tends to take up available resources when doing this. That would be a sign that good things are happening....like it is working.
~D

Okay, thanks for the replies guys.