More specifically, when I was a child my parents called Slumberland "Spinkot". They would say "Off to Spinkot!" instead of "Off to bed!". My father (of Czech and Russian ancestry) now has no idea where he got it from and a google search has provided little. The closest I found were the Czech word for "slumber": spánek and the Russian word for sleep: "спать". It's possible my father, having heard it from his parents, over time altered the pronunciation.
This brought a curiosity for the ways other languages talk about sleep.