Hallucinatory Sleep Disorder vs. Night Terrors

Hi Everyone,
I need some guidance. I have severe obstructive sleep apnea so I am well aware how serious sleep disorders can be. I am convinced that my mother has a sleep disorder but I think it's either night terrors or hallucinatory sleep problems............most likely the latter one. I almost have her convinced to go to a sleep clinic but in the meantime told her I would look up some information on the internet. I haven't found much SUBSTANTIAL information. Most sites jump around a lot. Does anyone have any good information - definitions, symptoms, effective medications and such to offer? Any GOOD websites?
Thanks so much for your help!