A memory foam or Purple mattress/pillow might help, they isolate movements when you lay on them. You might experiment with making a sort of 'child seat' made of

A memory foam or Purple mattress/pillow might help, they isolate movements when you lay on them. You might experiment with making a sort of 'child seat' made of the foam, which you might be able to get from a used mattress? You can also buy memory foam toppers which are somewhat cheaper than a full mattress. However, one part of me thinks that if you ever rode on an Amtrak train, you'd never complain about movement on European railways again =]