The present invention relates more specifically to the use of a source of green light for activating L-amino acid oxidase in the presence of at least one substrate of this enzyme in order to stimulate the energy metabolism of the cells of the skin, to stimulate their replacement and thus to improve the appearance of the skin and hair, in particular to prevent and/or treat cutaneous signs of ageing of the skin and hair. The invention also relates to a composition comprising at least one substrate of the enzyme and at least one substrate capable of emitting green light, to a kit comprising a green light device and the composition comprising at least one substrate of the said enzyme and to a cosmetic method employing the compositions or kits according to the invention.
