Abstract: The invention relates to a low-pressure gas-discharge lamp which, with its light in the red spectral region, influences the biological circadian rhythm by controlling melatonin secretion. The tubular glass discharge vessel, which can also be in the shape of a double helix, is filled with a noble gas or noble-gas mixture and mercury. Electrodes for the supply of energy are arranged at both ends of the discharge vessel. The discharge vessel is multicoated on the inside by phosphor layers applied one after the other. The first phosphor layer located on the glass surface consists of phosphor which is excited both by ultraviolet mercury radiation between 180 nm and 400 nm and also by the blue radiation between 400 nm and 490 nm emitted by the mercury discharge, and by the visible radiation emitted by the second or further phosphor layers between 400 nm and 550 nm, where visible light having emission maxima in the region between 500 nm and 650 nm is generated.