My neighbour across the street is freaking me out. I think she has some kind of security system.She is away a lot and there' s a constant round blue light on a DVD looking machine. I can't help but see it as she leaves a light on and her curtains wide open. Is she spying on me or am I jumping to conclusions?

Good advice from Bill Boyd.

These days surveillance costs little so there is a lot more of it, often where it is least expected and people don't like it - if they know about it; they see it as an invasion of privacy.

The fact is there is much more surveillance we don't know about than that we do know about. We know it is happening but as we don't know precisely where or who we mostly don't worry so why should we worry when we do know.
The fact is if we have nothing to hide, we have nothing to fear from it - right?

To find out what is going on do the logical thing
go knock on her door and politely ask what it all means
Then explain politely that is affecting your peace of mind and ask if she minds closing the curtains or ask if she can do something different
Sitting at home and wondering about it is making you loose your mind and the explanation and remedy is simply a matter of talking direct to the neighbour in a polite non abrasive manner