Sorry, I haven't got much to actually help with the tiredness, although for me sometimes a fruit juice and sparkly water combo helps. But for naps, could you just plonk the kids in front of the tv for half an hour and sleep on the sofa? I've perfected that art this first trimester. I don't sleep deeply and wake up at the slightest thing, so I have no safety concerns. Plus we pick educational shows so my guilt doesn't get too bad (current favourites: Andy's wild adventures and Nina and the neurons). Depends on your kids' ages of course though and whether they'd sit quietly for half an hour or not. We also put on audiobooks sometimes and I have a rest on the sofa while they draw or play. Or could you get a friend to watch them, even for an hour every so often? Or maybe you could pay a local teenager to entertain the kids while you have a rest?