Here is some informative information to help you understand  how hair grows, Let's start by how hair grows and increasing it's ability to grow. African Americans hair grows like a wirey sponge &  essentail  of moister which are exspose to the enviroment  while using many harmful products that disturbs & blocks the follicle depriving it of nutrients like heavy compounds such as wax, grease's & debris choking the follicle causing thinner hair until it eventually shuts down restricting new hair from coming threw the hair shaft. This is call DHT- dihydrotestosterone.  Hair normally grows at 1/2 inch a month going threw three stage's. The first is call ( Anagen phase when leaving the follicle they no longer have nourishment's from the Capillarie blood supply & so it dies. As it dies it is transform into a hard protein call ( Keratin)  which is also the material that produce's finger nails & toenails. Each hair we see above the skin is dead protein, So it is essential that most nutrients comes from the ( Capillarie vessel blood supply, meaning the root!  2nd stage ( Catgen- which the hair bulb detaches from it's supply pushing the hair up & out. It is normal to lose 50 - 100 hairs strands each day. All thou there are two FDA approve hair loss treatments ( Monoxide & Finasteride both that contain harsh  alcohol base solution that dries the hair causing breakage to which balance moister is crucial to exotic hair. It does however unblock DHT build-up but cause's stress to hair above the shaft. Other problems can come from changes in your diet, medications, stress, & even genetic age density. Some women may exspriances  hair thinning from  hormonal , menopause, & medications,  Hair piece closers can also cause poor air ventilation suffocating the shaft. Providing a strict hygiene regimen also promotes oxygen blood circulation & stimulation & should be perform weekly followed by vitamins multi oils  may require some touch-up's according to style?