Some evidence suggests stress may accelerate premature graying, but the relationship needs more research.
A large cross-sectional study of over 2,600 medical students and residents found that higher stress levels were associated with earlier onset of gray hair before age 25. However, this single observational study cannot establish causation, and the evidence base is too limited to make definitive conclusions about whether stress directly causes gray hair.
Caveats
Only one observational study available; cannot prove causation; multiple other factors like genetics, nutrition, and lifestyle also influence premature graying