Given the docking station is basically a USB peripheral that supplies power? Being able to unplug and replug USB peripherals while asleep seems like a reasonable expectation to me.
No it's not. Assuming the OP means something vaguely modern, it'll be a Thunderbolt dock that shares PCIe devices to the host. Try and work out the complexity of a PCIe device disappearing while you're "asleep" in your head. Trust me, you don't want to go there.
