This may be a bit of a different post to normal, but I'd really appreciate any help.

I've long suffered depression / anxiety myself, and have it mostly under control and stable.

My sister on the other hand has been depressed for 2ish years. She constantly says things like "can I die yet?", "please can someone murder me", "I don't want to live any more". And she can be in bed all day, and if you try and speak to her she'll reply with some unintelligible noise, you'll have to ask her to repeat every word 2 or 3 times before you understand what she's saying. I understand this can all be caused by depression.

She takes anti-depressants and sees someone for CBT. She's been getting worse the last few weeks, having week's off work sick etc, staying in bed all day crying etc. She also refuses to take any praise. For instance if she does some excersise I'll praise her for it, but she'll respond with "I did shit. Worse workout ever." I'll say something like "It's good that you even did it, you can be proud of that" and she'll say "No, it's shit".

She also claims to have never been happy her entire life. Which I know for a fact is bullshit, I grew up with her! Is she consciously making that up?

BUT, and this is the part I'm struggling to understand. She can be in bed all day, barely able to pronounce a word that I can understand, but then 30 minutes later, she can be getting dressed up to go out with her friends, be speaking very clearly (and very fast) running around the house doing her make-up etc.

I know that if I was depressed and in bed all day, I'd be more likely to cancel plans than suddenly be excited by them. Which has happened to me plenty of times. And even when I found the motivation, I often left the night early.

How is it possible to go from the extremes like that? Is she 'putting it on' a bit when she's at home, looking for extra sympathy? That might explain the very low effort 'words'. I don't think she's putting it on though...

Could it be bi-polar?

How can I help when she won't take any praise, or advice (cutting down on the alcohol as it's a depressant etc)?

My anxiety is sky-high right now, mainly because of worrying about her depression. Which is kind of ironic.