Actually, a lot of these newfangled theories are just old-school statements of the obvious.
The “drink more water” theory encourages you to drink plenty of water—but you don’t see people who don’t drink water anymore. The “get plenty of sleep” theory encourages you to sleep through the night—but plenty of people who don’t get enough sleep don’t make it past their 40s.
Then there’s the “braking” theory: if you’re driving fast and a huge truck suddenly appears ahead, slamming on the brakes increases your chances of survival. You don’t see the people who don’t slam on the brakes anymore, either.
The “drink more water” theory encourages you to drink plenty of water—but you don’t see people who don’t drink water anymore. The “get plenty of sleep” theory encourages you to sleep through the night—but plenty of people who don’t get enough sleep don’t make it past their 40s.
Then there’s the “braking” theory: if you’re driving fast and a huge truck suddenly appears ahead, slamming on the brakes increases your chances of survival. You don’t see the people who don’t slam on the brakes anymore, either.