Encyclopedia
Reference entry
Physiology
Cortisol
A hormone released under stress; implicated in changes to the hair growth cycle.
Soumm · Physiology
Definition
A glucocorticoid hormone central to the body’s stress response, with wide effects on metabolism, immune function and tissue repair.
Sustained elevation is associated with earlier entry of follicles into their resting phase.
What is uncertain
The threshold at which everyday stress becomes significant for hair is not well defined, and individual variation is large.
See also: Stress, Telogen Effluvium.
A note on evidence
Hair responds to many things at once: sleep, nutrition, hormonal changes, scalp condition and stress among them. Published here for education only; individual concerns should be discussed with a qualified healthcare professional.