Yes you're spot on.
It is very easy to go to the negative astrals by mistake when you are dreaming. It can either give you horrible nightmares, or mean that you just don't remember your dreams because they were too traumatic.
You can ask your astral guide before you go to sleep to make sure that you only have experiences in the positive astrals when you dream. If you find that doesn't work you might have a portalway open to the negative astrals which an soul realignment practitioner would be able to close for you, or you could probably ask for the portalway to be closed by asking your guides to close it for you.
I don't know if we are taught anything through going to the negative astrals. I know some souls go there in an effort to help other souls that might have got stuck there.
Hope that helps.
