Gotcha, this is a fascinating question. Firstly I have to say that I don't know the answer to it. However, I watched a series by the BBC about the brain a few months ago and it certainly seems that some people are prone to these kinds of experiences. In fact, scientists have been able to produce these reactions in people by stimulating certain parts of the brain with electrical pulses.
You would have beens seriously rivited to this program - I so wish I could remember more to tell you. I will ask David as he saw the program too and we both realised that there are often very rational explanations for what some people claim to be supernatural events.
I feel we are only just beginning to unlock the secrets about the brain and how it works. I believe your mother very probably imagines spirit attacks. Mmmm, is she very attractive??? Hehehe - couldn't resist tha (Aussie humor)t. I have never had anything like a spirit attack, and I'm not that bloody ugly :-)))) Actually though I am prone to weird behavior in my sleep. A lot of talking and seeing things and ordering people about. Sometimes I wake up in mid performance, and feel a right idiot. My tendency to let out blood curdling screams upsets my husband a lot when I do it. I mean to say no one wants to be woken in the dead of night with a mad woman next to them screaming their head off. I could always misinterpret this stuff as being supernatural - as I have at times imagined that I've seen things and I often react as if I have. But I know with certainty that I'm asleep and my mind is doing all this stuff (especially when there's a full mood) HOWL!!!!. Hey's it's Halloween tomorrow? What a good sense of timing you have!!
Another aspect of this is: If the demon stuff (according to the wTS) is true, how come the rest of it is such crap? The WTS is basically wrong in just about most of what they do and say, so I tend to think that there has to be a better explanation about the demon stuff for your mom - though I realise that getting her to believe that is another matter entirely.
good luck hehehe!!
Marilyn (who has often pondered the same question - based on what others claim to experience)