Lately we've been having issues with the electric grid, and now I'm noticing that my ceiling lamps are all momentarily dimming (I'm not sure if that's the right word). It's not flickering since the light doesn't goes off; it just loses "strength" for about a second or so and then goes back to its "regular" intensity.

The microwave is also momentarily losing power while heating something: the light dims a bit for a second or so.

I'm no electrician, but I'm sure this hurts our appliances. So what can I purchase to regulate these electric fluctuations?