The problem with writing while the children are sleeping, which is exactly what has happened this summer, is that I'm shattered most of the time. It's classic burning the candle at both ends and I'm nearly burnt out...but happy.
I'm really enjoying working on my character biogs, with the hard work and disillusionment still ahead. Jurgen Wolff's excellent book, "Your Writing Coach" has a lot of helpful guidance at this stage of creating, and I'd recommend it if you're in need of any advice.
For me, this stage is a bit like being in love. My main character is in my mind nearly all the time; she came with me today to hang my washing out with me, and we had an interesting discussion about euthanasia (which is funny, as it's not an issue that will arise in the book, I don't think). I find myself dwelling on incidents in her past that will probably never come to light; I'm tempted to write episodes from her backstory, just to ground her in my mind. I think I dreamt of her last night. I feel like a stalker...in a fictional character's life. And now it's time to move onto her husband...ha ha ha.
Love this writing lark....don't you?