You don't need to retire to a cloister or the desert for years on end to experience a true dark night; you don't even have to be pursuing any particular "spiritual" path. Raising a challenged child, or caring for a failing parent for years on end, is at least as purgative as donning robes and shaving one's head; to endure a mediocre work situation for the sake of the paycheck that sustains a family demands at least as much in the way of daily surrender to years of pristine silence in a monastery. No one can know in advance how and where the night will come, and what form God's darkness will take.