DD1 has never been a great sleeper, but when she wakes at night she will usually go back to sleep, sometimes even without any intervention from us. But during the day she will never sleep longer than one cycle, and nothing will persuade her to go back to sleep once she's woken up.
We're lucky if she sleeps for an hour in the day, usually she wakes after 40-50 minutes. Things are better than they were, as during the 9 month sleep regression she'd only sleep for 20-30 minutes at a time, but it's still a problem, especially as she's clearly still tired when she wakes up, and is constantly yawning and grizzly. We have blackout blinds, so it's pitch black in her room, so that's not the problem.
Any ideas?