Advice like this turns almost everybody's normal state into a disorder.

"Go to sleep only when you are very tired" is a child's approach to sleep, it's what we all want to do, and by adulthood we learn that it's counterproductive. But we still want it so much that we regularly test it and are reminded why we don't operate that way.

It reminds me of the intuitive eating folks who say, "Ignore standard diet advice, just listen to your body and feed it what it knows you need," but then when you overeat, they say, "You aren't listening properly, you aren't in tune with your body." Then if you ask, "How will I know when I'm in tune with my body and listening to it properly?" they say, "When what it asks for matches standard diet advice."

>> sleep only when you are very tired

This flies in the face of all sleep research done at the Stanford Health Care’s Sleep Medicine Center.

You're confusing treatment for insomnia with recommendations for general sleep hygiene.

Wake up without an alarm clock is surely beneficial regardless of when you go to sleep?

or have even a single obligation in the morning