My recent saving grace for Santi's sleeping routine is this CD, Marga, my sister-in-law-to-be passed to me when I gave birth.
At first, I didn't bother playing it and stashed it somewhere in the room. Recently, however, I finally gave it my time of day since I was lured by the album cover that says "STOPS CRYING GUARANTEED!"
It is really remarkable! Santi seems to be napping more frequently and for longer periods. How fab is that?!
The obvious explanation- babies listen to the rhythm of the heartbeat for nine months. Thus, they become accustomed and soothed by it.
Now, if only the CD had a track of the heartbeat alone, sans the lullaby. It can get irritating (to mums & dads) if it's been playing all day long! But then again, for Santi to sleep peacefully, I'd do anything... in a heartbeat ;)