Respiratory humidifier and lighting device for respiratory humidifier

A respiratory humidifier with a lighting device to facilitate observation of the fill level of water in a liquid container from which humidity is added to the breathing gas, the humidifier including a housing with a heating plate and the liquid container with a bottom plate which, when brought into contact with the heating plate, heats the liquid in the liquid container, wherein:

• the housing includes a projecting portion having a downwardly-facing wall surface with a light-exit portion, the housing containing an electrical light source directed toward the light-exit portion such that light from the electrical light source exits downwardly therefrom;
• the liquid container includes an upwardly-facing light-entrance portion directly adjacent to and facing the light-exit portion and positioned above the water therein such that light proceeds from the light source through the light-exit portion and light-entrance portion downwardly into the liquid container to illuminate the surface of the water, and at least certain parts of the container surfaces of the liquid container being transparent.