Ultraviolet (UV) radiation can cause skin problems like accelerated aging and cancer, but it will not interrupt hair follicle function. However, overexposure of hair fibers to UV radiation can in fact weaken the fibers, disrupt the cuticle and make them more prone to dullness, frizz and breakage.
What you inherit is the sensitivity to dihydrotestosterone or DHT (a hormone and natural compound of testosterone) that can cause hair loss in men and some women. If you're male and you take testosterone, it could accelerate the hair loss process.
There are approximately 200 genes that regulate hair and hair growth. We know today that there are generally some genes from both sides of the family that play a role. Your mother’s father deserves some of the 'blame’ but perhaps not all of it.
Medications or laser therapy, for example, can help hair follicles grow thicker and healthier, therefore appear to be fuller.
The good news is pulling out grey hairs won't make more grow back. The bad news is most people get grey hair as they age anyway.
Many people may notice they shed daily after they shampoo or brush their hair. Hair follicles cycle on and cycle off and repeat that process over the course of their life span, each day we can lose up to 100 to 200 hairs and these hair follicles are replaced by other hair follicles entering the growth phase.
It may sound funny, but this is a commonly heard myth. Hair loss is not a blood flow problem, but instead can be caused by other factors like age and genetics. "Even if increased blood flow helped hair growth, you could not stay in that position long enough to have an effect on the hair follicles.
Wearing a hat can cause hair loss.
While people may believe that hats may cause hair loss, there is NO evidence scientific or otherwise to prove this.