kitsune...another thing. i think a 'standard routine' n nice sleeping environment also helps. Thanks to my mum, ruth's routine quite fixed - in the sense that time to eat, time to play, time to sleep though not FIXED time, but the sequence is somewhat there.
Also, my room is quite 'noisy' - a lot of road sound n etc. she sleeps pretty well.
my mum's place, she sleeps to my mum's erm...cantonese/hokkien/chinese karaoke music! if too quiet she will wake up! but of course not like...market like that la!