Very clever Kitty and very patient you, Jo. My four all troupe upstairs to their night-time beds in my bedroom (there's not much clear floor space). If anyone needs out in the night, they get up and shake their heads vigorously to wake me up then head for the stairs. I have a night light at the foot of the stairs as Jock (now 13) sometimes bags the sofa downstairs for a while and doesn't like climbing the stairs in the dark.
They also go there on the rare occasions that I go out and leave them, as they can hear the car scrunching the gravel when I come back - the allotted sentry jumps on my bed and looks out the window to make sure it's me then they all tear downstairs to be behind the front door when I open it!
I'm sure Kitty will love her upstairs bed more and more as time goes on.

Thank you Marion for your lovely reply. I enjoyed reading about how your four act upstairs. Kitty has not quite got that far yet, but when I turn the lights out she comes up and puts her nose to mine to check me out before going to her own. She has not yet tried to join me on my bed, but loves stealing things from it given half the chance! I also have to be careful to hang my clothes out of reach or she will collect them and take them to bed with her.