Sometimes I wake up in the middle of the night and wonder where I am. This used to happen more often when we traveled by RV but it still happens in the boat. The game I play is to try to remember before I open my eyes. For bonus points, I try to remember where I left the boat (previously, RV).
In the first few seconds of wakefulness, I have to guess whether I'm in my bed at home or on my boat. If I guess that I'm on the boat, then I have to remember what marina or bay I'm in. If I can also remember which way the boat/RV was headed when I docked/parked it, then I figure I've got my wits pretty much about me and it's safe to open my eyes.