That reminds me of solipsism* : the idea that your own mind is the only thing surely existing and might contain everything else; the universe, other minds within.
Sometimes before falling asleep I wonder if the instance of my mind that wakes up is really the same mind or just someone else with the same memories and body as my mind.
Fortunately this doesn't actually stop me falling asleep.
Fortunately this doesn't actually stop me falling asleep.