Cosmo Hair Clinic

Pulling hair too tight -- as can happen with ponytails, braids, and cornrows -- can damage hair follicles and cause hair to break or fall out. Hair extensions and hairpieces can sometimes cause traction alopecia, too, because their extra weight pulls on existing hair. Changing your hairstyle usually lets hair grow back. Pulling hair back tightly for a long time, though, can lead to permanent hair loss.

In alopecia areata, your immune system mistakenly attacks hair follicles, causing hair to fall out -- often suddenly. Most people will have one or two bald patches, but in some cases all body hair falls out