I've been waking at 3 a.m. and tossing until 5 a.m., not alert enough to sit up and read, not dead-enough-to-the-world to sleep. This afternoon, I went down for a brief nap. I dreamed that I was in a car as it sank into a lake, water flooding in through the partly opened driver's side window. The window wasn't quite opened far enough for me to slip through, so I had to roll it down, but couldn't, with the water pressure on it. So, I knew I had to wait for the car to flood, and hold my breath, while the pressure equalized on the glass before I could slip out and up for the surface. I didn't know if I could refrain from panicking or hold by breath long enough to get out of there alive. Fitful in my afternoon nap, I awoke before finding out.
Keeping calm while the ambient pressure re-equalizes.... That's about right.