Jerking yourself upright from a slumped position in a chair after a bout of sleep apnea does not constitute a “sit up”.
As to Reid’s apparently somewhat severe injuries, I’m inclining more and more to commenter R-man’s theory that the Koch brothers roughed him up.
Charles: My, my, David, da senator looks like he musta had a fall – from, say, one a dem exercise contraptions [extracts handkerchief from jacket pocket and wipes the blood off his knuckles].
David: Yeh, dat’s da way it looks to me, Charles. Just like he took a long walk on a short treadmill. Good t’ing it wasn’t a long walk on a short pier - which is sometimes what happens to guys what exercise their mout’s too much [stomps an imaginary cockroach crawling across the senator’s ribcage].
Charles: Truer woids was never spoke, Dave. Ya got dat, senator? Ya fell. Off a exercise machine. All by yer lonesome.
Reid [moaning]: Uhnnn…fell…exercise machine…
David: Maybe youse would like a ride home, eh, senator?
Reid: No! Don’t…want to trouble you…will call…a cab…
Charles: Well, suit yerself, bub. Now, one more time, just ta make sure yez got it right. What happened to yez?
Reid: I…I fell off an exercise machine.
Charles: Good boy. By da way, about dat eye; ya can’t go wrong followin’ ex-President Clinton’s advice to dat broad: ya might wanna put some ice on dat. C’mon, Dave. I got dis primonotion dat Congressman Boehner is about to take a tumble down da steps out front a’ da tannin’ saloon.
David: Well, let’s hustle on over dere and see if yer primonotion pans out.
Charles: My primonotions always pan out, Dave. Sometimes ya just gotta give ‘em a little boost, ya know?
Update: Smitty over at the other McCain takes a deep dive and develops his own theory.