Copper peptides (GHK Cu) have been studied for decades for their role in tissue repair and that same biology applies to hair. Research shows GHK Cu may help strengthen existing hair follicles, reduce Ingredients Hairgenetix GHK Cu, AHK Cu & PDRN Peptides Neurogan Health, GHK Cu Copper Peptide, Hair & Scalp Serum Hair Growth Cycle: The Circular Life & Death of Follicles Anagen Follicles Regrowth Cycles & All You Need to Know How long does the anagen phase last? How many hairs are in the telogen phase ?