Note to self - overnight buses in Bolivia are less comfortable than those in Peru; you won't arrive at your destination (Sucre, in this case) as well slept as when taking overnight buses in Peru. Factor on needing coffee more than usual.
The sleep wasn't helped by a bloke puking into a bag during the journey, where I've no idea why he didn't use the toilet which was a whole 2 steps from his seat.
On a journey which was meant to take 12 hours it was actually just under 13, which isn't bad for Bolivia.
Greetings from Sucre - a place far more sedate than La Paz, but there are probably war zones which are more sedate than La Paz.
Update: oh, and Bolivian buses are much colder than Peruvian ones. Strongly consider bringing something warm with you - last night my down jacket was very welcome.