The invention relates to a low-pressure 
gas discharge lamp influencing the biological 
circadian rhythm by controlling 
melatonin secretion by means of the light thereof in the red spectral range. The tube-shaped glass 
discharge vessel, which can also be formed as a double 
helix, is filled with a 
noble gas or 
noble gas mixture and mercury. Electrodes for infeeding energy are disposed at both ends of the 
discharge vessel. The 
discharge vessel is coated on the inside in multiple 
layers by successively applied fluorescent 
layers. The first fluorescent layer is made of an illuminant excited by the 
ultraviolet mercury 
radiation between 180 nm and 400 nm, and by the blue 
radiation between 400 nm and 490 nm emitted by the mercury discharge, and by the emitted 
visible radiation of the second or further fluorescent layer between 400 and 550 nm, wherein visible light having emissions maxima in the range from 500 nm to 650 nm is generated. Together with light sources for 
melatonin suppression, the low-pressure 
gas discharge lamp, having warm light thereof, is particularly suitable for simulating the quasi-
circadian rhythm of an individual when external conditions, such as 
sunlight, are missing. Due to the good 
color reproduction and 
high energy efficiency thereof, it meets all necessary requirements of a 
light source for illumination tasks, and is therefore also suitable for general lighting.