The Persona
Dreaming of hair falling out: meaning and interpretation
The strength that shows
Image, vitality and control over how others see you. Hair falling out in a dream does not predict illness.
Symbolic reading
Hair is what grows from you and what you show the world. Dreaming that it falls out, that someone cuts it or that it suddenly changes often speaks of image, of control, or of a strength you feel slipping away. If you were cutting it yourself, something may be asking to be renewed; if someone took it from you, look at where you feel others decide for you. It is not an omen about your health.
Jungian key
In analytical psychology, hair belongs to the Persona, the face we offer the world, and also to life force, as in the story of Samson. Losing it in a dream can be the fear of being exposed; it can also be the chance to show yourself unadorned.
Who you are does not fall out with a strand of hair. See which part of your image is asking for rest.