My MHCN says that the new advice suggests solids from 4 months is a good idea (at least for some babies, evidently). I'm not certain of the reasons - something to do with allergies, I think. Not that we're close to that yet, with DD (nearly 7 weeks old now).

Anna, I feel for you. Hope you all get more sleep tonight. Can you and your partner take it in turns, maybe with one of you sleeping elsewhere, so at least someone is getting some sleep? One of the things that helps us stay sane with a newborn is having DH get more sleep at night, but be able to take DD for a while while I catch up somewhat during the day.