DH has been playing "loscil" to DD on a few occasions now and every time she is aleep during her bottle (15mins) and stays down instead of 3hour battle of bottle, then breastfeeding, shh patting and so on!
It is very soothing electronic/ambient music (probably a bit womblike but more variety than your bog standard white noise!)
Thought I would share incase it helps other sleep deprived parents! (in fact maybe we should conduct a mumsnet sleep experiment!)