OK.....I'm unresigning.
It says.....it is a term used to describe 'a period of time'. Not all societies, not a group of people....not a majority, or even a general population or percentage. It's a name for
a period of time that some people experience. It doesn't suggest that everyone suffers it or that it is an occurance to be expected by all.
Not unlike the 'empty nest syndrome'. Some people go through long bouts of depression, feeling that their importance in life is over, while others have their kids rooms turned into a pool room, just so they can have a table to dance on, before their clothes are even packed.