Lamp, in particular a lamp for street lighting, having - a lighting means, in particular an LED, having a main light emission direction, - a reflector for emitting light indirectly into the environment, which reflector is arranged in front of the lighting means in the main light emission direction, - a support for supporting the lighting means, which support is provided on the rear side of the lighting means with respect to the main light emission direction, and - a heat sink which extends between the support and the lighting means, wherein the heat sink has: ∘ a receiving side with which the lighting means is thermally coupled, ∘ a heat conducting structure which extends away from the receiving side in the opposite direction to the main light emission direction toward the support, ∘ a side wall which completely surrounds the heat conducting structure laterally on the outside circumferential side and which is designed as a reflector on the side facing away from the heat conducting structure in order to reflect the light reflected by the reflector which is arranged in front of the lighting means, wherein the side wall has at least one inlet opening and the receiving side has at least one outlet opening, which openings are fluidically connected to one another via a cooling channel formed by the heat conducting structure in order to dissipate heat, which is transferred from the lighting means into the heat conducting structure, by means of convection via the cooling channel. - a lighting means, in particular an LED, having a main light emission direction, - a reflector for emitting light indirectly into the environment, which reflector is arranged in front of the lighting means in the main light emission direction, - a support for supporting the lighting means, which support is provided on the rear side of the lighting means with respect to the main light emission direction, and - a heat sink which extends between the support and the lighting means, wherein the heat sink has: ∘ a receiving side with which the lighting means is thermally coupled, ∘ a heat conducting structure which extends away from the receiving side in the opposite direction to the main light emission direction toward the support, ∘ a side wall which completely surrounds the heat conducting structure laterally on the outside circumferential side and which is designed as a reflector on the side facing away from the heat conducting structure in order to reflect the light reflected by the reflector which is arranged in front of the lighting means, wherein the side wall has at least one inlet opening and the receiving side has at least one outlet opening, which openings are fluidically connected to one another via a cooling channel formed by the heat conducting structure in order to dissipate heat, which is transferred from the lighting means into the heat conducting structure, by means of convection via the cooling channel. ∘ a receiving side with which the lighting means is thermally coupled, ∘ a heat conducting structure which extends away from the receiving side in the opposite direction to the main light emission direction toward the support, ∘ a side wall which completely surrounds the heat conducting structure laterally on the outside circumferential side and which is designed as a reflector on the side facing away from the heat conducting structure in order to reflect the light reflected by the reflector which is arranged in front of the lighting means,