DS used to fall asleep to:
a) Tape of classical music played in 4/4 that came with the nervous first-time mother's "how to play with baby's" pack (retailing at a moderate £2 million). Rumoured to increase the bit of brain that would later deal with maths. Poor sod got that every night for months!
b) Glaswegian DP singing:
Cammerton Loch I wish you were whisky
Cammerton Loch Och aye
Cammerton Loch I wish you were whisky
I would drink you dry
(to of a sort of eightsome reel with imaginary bagpipes)