Well... Where to start? I have dealt with Night Terrors in my daughter and her father (when we were together). Both were because they fought sleep and were overtired when they finally did go to sleep. My daughter has had sleep walking episodes as well and my ex sil informed me that my ex did too. With my ex, I HAD to wake him up because he'd hurt himself or me in the process. I used to have to mule kick him to get him to stop having fits of swinging, screaming, turning lights on, yanking things off the walls, darned near knocking a 90gal fish tank over, wetting the bed, and whatever else you could think of. And yes... I said wetting the bed... From a 30yr old man.
As far as my daughter goes, I will go into her room and usually just sitting on the edge of her bed would wake her up and snap her out of her Night Terror. And as soon as she'd wake up, she'd stop screaming and sobbing, hug me, and we'd talk for a few minutes. She doesn't even know why she was crying.
The difference between a Night Terror and a Nightmare is the state of sleep that it occurs in. During REM is when we should be dreaming. Non-REM is when we should be completely at rest. That's when we have a neurotransmitter send out relaxants into our bodies to keep us immobile. In a person with Night terrors, that relaxant is never released and during non-REM is when they have this Night Terror (when it shouldn't be, but is). This is what makes people with Night Terrors so exhausted the following day. They never had the good restful Non-REM sleep they're supposed to get.
If you have any questions about sleep disorders, don't hesitate to ask. I've been through a sleep study, got diagnosed with Hypersomnia. My hubby has Apnea. My ex has night terrors (along with our daughter) and sleep walking. My aunt has RLS. I've learned A LOT about them. My sleep specialist was very surprised that I learned as much as I have. : )