Figure 2. Spectral composition of room light in which mice were caged.

The spectrum was measured directly under the room light which had an opaque cover (blue line) and again in the cage (red line), which did not receive any direct room illumination. The measurements for the cage are X 10 of those for the room light. As common with room lighting, it is primarily composed of a series of discrete peaks, however none of these are close to 670 nm.