Rats and bright light: why they need dark hideouts in their cage
A pet rat's ears and nose aren't the only senses that work very differently from ours - its eyes do too. A landmark review by Charlotte Burn, published in 2008 in Applied Animal Behaviour Science, describes a species that is extremely sensitive to light, to the point that poorly chosen artificial lighting can, over time, damage its retina (Google Scholar search). Find more housing tips in our bedding and habitat section.
An eye built for darkness
Rats are mainly nocturnal and crepuscular, and their retina has adapted to very low light. Their vision extends into the ultraviolet, a range we cannot perceive at all, but it copes poorly with bright, continuous light. Red-eyed rats, which lack the protective pigment found in dark-coated, black-eyed animals, are even more sensitive to it.
Where (not) to place the cage
A bright living room, a cage set right next to a south-facing window, or an overhead light left on all evening expose the animal to far more light than a wild rat would ever encounter - a species that is mostly active at dusk. It's best to place the cage in a corner away from direct sun and to dim strong lights in the evening, exactly when the rat becomes most active.
Genuinely dark corners
Beyond where the cage sits, rats need truly opaque hideouts to retreat to during the day: an enclosed house rather than a simple saucer-shaped shelter, a hammock draped with thick fabric, or a solid wood house like those covered in our rodent hideout materials guide. A rat hammock, hung up high and closed on top, does double duty as both a bed and a shield from the light. For overall enclosure sizing, see also what cage for a rat.
Frequently asked questions
Does the room need to be pitch black during the day?
No, normal ambient light is fine; what matters is that the rat always has at least one opaque hideout it can retreat to whenever it wants.
Are dark-eyed rats completely unaffected?
No, they are still mainly nocturnal animals and also benefit from dark corners, even though their pigmentation protects them better than a red-eyed rat's.
Is a night light in the room a problem?
A dim red light is usually well tolerated; it's mainly bright, prolonged white lighting near the cage that should be avoided.
This guide is part of Planète Pets’s Rodents universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.