Good hair days aren’t a myth. When you take a closer look, they’re simply hiding behind the right science. Peptides: the buzzy ingredient that has massively moved from skincare royalty into my haircare routine. These tiny chains of amino acids that are hair growth actives, popping up everywhere in serums, tonics and treatments promising thicker, stronger hair. “Peptides are naturally occurring molecules composed of amino acids, the foundational units of proteins,” Michelle Green, MD , board-