a sacrifice that is comely for a woman who intends to pray, and prayer is a major part of our sacrifice to God.  If a woman intends to pray or prophesy, she should have uncut hair.  Which would be as long as her God-given length will allow.

SPECIAL TIPS to African American women
If you wish to have longer hair.  Firstly, hair growth is directly related to circulation.  Good circulation that goes all the way to the top of the crown can produce healthy hair growth. 
Good eating habits which shun fatty and excessive fried and fast food and sugars can be instrumental in producing good circulation.  So can vitamins and an aspirin as your doctor dictates ( the latter).
A good brand of vitamins can be bought over the counter, but a proven brand of vitamin that has grown "black" hair is called "
BODY WISE RIGHT CHOICE PM MULTI-FORMULA by Body Wise International."  This vitamin produces rapid hair growth. (Though this is not a claim of the company, this IS a PROVEN result.) It may not produce growth on bald spots.
Good hair growth will be more satisfying in one learns to treat it correctly.  A good shampoo and conditioner, such as Infusium23 is good for the hair.  There are also other good brands.  A mixture of Infusium23 leave in conditioner and glycerin will prevent much hair breakage.  This will result in pleasant results.
Hair must be moisturized to prevent breaking.
Another hair treatment for those setting your hair is
GOOD COSMETOLOGIST can encourage hair growth also, but don't let them fool you, you do not need to cut or trim your hair for it to grow.
I have an African American girlfriend who has never cut her hair.  when we were in High school, her hair was just beneath shoulder length.  when I saw her years later her hair was at least one and one half feet longer!   She did it by simply rolling the end of her hair in a pony tail.  Rolling the hair at night will also encourage hair growth.  Sorry Cosmetology Board�tsk..tsk.
Remember ladies, when you were small your hair grew without cutting it!  If you want it long, leave the cutting alone!  Why cut off what you want to keep, such as HAIR?

Also,  Drugs can cause hair loss.