American Fancy Rat & Mouse Association

This article is from the WSSF 2016 AFRMA Rat & Mouse Tales news-magazine.

Beginners’ Corner

Light Sensitivity

By Karen Robbins

Q I am very interested in attempting to learn more about rat or rodent behavior, in particular, how light affects them physiologically and psychologically, including their avoidance of bright light. I find that rats and mice are most sensitive to the colors of green and blue. But because rats don’t have many cones, I was trying to find out, for instance, if they would be more sensitive perhaps to white light than green of the same intensity or the reverse. Could you provide more information about this or direct me to a source or sources? Thank you for your assistance.

A We have three articles regarding how light is harmful to rodent eyes: Rats and Sunlight, Blind Rat, Eye Discharge. And on the Rat Behavior and Biology web site are these articles What Do Rats See? and The Rat’s Eyes. In a Google search I found Cone-based vision of rats for ultraviolet and visible lights and Ophthalmology of Exotic Pets, Chapter 7.

In doing other research I found how lighting can have various negative effects on rodents:

  • Unthrifty young, shorter breeding lives, smaller litters, and shorter life for mice housed under pink light than seen with natural or white light
  • Retinal degeneration within 3–7 days in albino rats when exposed to high light intensities which then caused increased stress
  • Continuous exposure to dim light (no dark cycle) is phototoxic to rats
  • Prolonged estrous cycle in mice and rats with longer light cycles; the estrous cycle in rats changed from the normal 4 days with 12 hours light/12 hours dark, to 5 days with 16L/8D, to becoming irregular with 22L/2D and would not reproduce.
  • Persistent estrus in female rats exposed to continuous red light
  • More fighting with male mice housed in continuous light for one week

We don’t have anything that specifically answers your questions. You can do a search on PubMed to see if you can find the answers to your questions. *

Updated December 15, 2021