There are life events that can destroy the personality, which is a lot more fragile than most people imagine, constructed as it is from bits provided by others in the most haphazard way. People can be torn down to the core, "shattered," as the expression goes, and then they seek sleep. And dreams, which provide the ground for the construction of a new and more integrated self. Providing there's a core, and providing they're willing to do the work.