Blind mice see

There’s more to vision than meets the eye.

Although unable to see, mice lacking rods

and cones in their retinas can tell day from

night. And their pupils still respond to

bright light.

These latest findings suggest that

mammals’ eyes contain another

light-sensitive pigment not found in rods

or cones. The pigment may regulate

circadian rhythms that govern sleep

patterns and other behaviours, such as

eating, that are related to general light

levels. Nature