Strictly speaking, stress doesn't cause ulcers. A bacterium does. Robert Sapolsky, author of the highly influential book Why Zebras Don't Get Ulcers, has been clear about that. But his famous phrase was never really about ulcers. It was about something more fundamental: why the human stress response is so easily, and so chronically, activated-long after any real danger has passed, and even in the absence of any danger at all.
When Shakespeare wrote "To sleep, perchance to dream," was he thinking wishfully? Remember when you could sleep anywhere, anytime? Your head hit the pillow and you were out until morning. Seems those days vanished somewhere between middle age and retirement, replaced by nights spent staring at the ceiling, performing word games on your smartphone, and tapping your charging Apple Watch to check on the time until it was light.