Opinions wanted

[Sejanus]

So I had roughly 6 hours sleep before I started my new job thanks to her.

...if knowingly depriving people of sleep before a very important event isn't being a bitch, then I don't know what is.

Thoughts?

(bold mine)
It sounds like you're adding unnecessary fuel to this fire - maybe projecting a bit?

When having a debate (argument) I find it is best not to presuppose the other participant's motivations.

ETA: To clarify. I'm not defending your sister. From your story, it sounds like she has selfish tendencies. Selfish people rarely put deliberate effort toward others. To presuppose that her motivation was to annoy you or to keep you up, may be giving her more credit than she deserves.

Perhaps... but I said she was knowingly depriving me of sleep because I made it clear to her that's what she was doing, and she continued to do it regardless.

I personally think that knocking on her door and pollitely requesting consideration might have worked better than knocking on the wall and demanding it.

That's not to say that she was right, she certainly isn't ... but Ma Thump had a lot to say about catching flies with honey and not vinegar.

It might've, but I know my sister, and I know had I done that, she probably would've been more quiet, but she wouldn't have stopped talking, and I would still have been kept awake.

After having an awkward college roommate for a year in a single room-dorm, I obtained a sleeping mask and some earplugs. Now that I'm in an apartment with 3 other people, I still find occasion to use them. Perhaps you may find value in such occult devices? Mind you, this is a side-stepping of the issue. If your sister behaves in such a way in response to your request for a sleep environment on a regular basis, then perhaps it's not in your best interest to maintain a familial relationship. I don't know what your financial situation is, but moving out may be in your best interest. Find a roommate who's easy to negotiate with.

It's not really a regular occurrence to be honest. The issue is more her inconsiderate nature and complete inability to recognise when she's wrong.