# Do we need to leave the lights on at night for our cat? **URL:** \ **Category:** Factual Questions\ **Created:** [February 21, 2010, 7:44pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904 "2010-02-21T19:44:09Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![MovieMogul](https://avatars.discourse-cdn.com/v4/letter/m/f08c70/32.png) [@MovieMogul](https://boards.straightdope.com/u/MovieMogul)\ **Post date:** [February 21, 2010, 7:44pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/1 "2010-02-21T19:44:09Z")
We have a cat that roams freely from our bedroom to the bathroom (where her box is) to the den (where her food & water are) all through the night. Despite my assertion that, being generally nocturnal, she doesn’t need the lights left on for her to navigate, my wife insists on leaving one on in the hallway that connects the three rooms. Note, this isn’t a night light but a fixture (on a dimmer, but still, fairly well-illuminated). Given her shock at our electric bill (which isn’t always high, but sometimes), I’m trying to find some way to save energy, and I figure not having the light on every single night would be a good start–but not if it’s at the cat’s real expense. So does she need that light on, or is my wife misguided in her insistence that it’s a common “myth” that cats can see well in the dark? ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [February 21, 2010, 8:02pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/2 "2010-02-21T20:02:37Z")
Even with a minimum of outside light coming in through the windows, the cat will see fine. And, for your electric bill: a 60 W bulb left on for 10 hrs each day costs you about $1.80 a month. If you’re looking for savings, look to 27/4 appliance efficiency (cooling, heating, fridge) and insulation/sealing (e.g., drafty windows). If you keep a big room lighted for extended periods, that might be a decent contributor, too, but it’s usually less than you think. ---
**Author:** ![Hello\_Again](https://avatars.discourse-cdn.com/v4/letter/h/85e7bf/32.png) [@Hello\_Again](https://boards.straightdope.com/u/Hello_Again)\ **Post date:** [February 21, 2010, 8:06pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/3 "2010-02-21T20:06:00Z")
Cat’s can’t “see in the dark” literally but their eyes’ ability to gather light is different from and superior to ours. The ambient light that would seem “almost pitch black” to us – like from the moon or the stars or a far away streetlight – is plenty for a cat. However if your wife is just absolutely convinced, get a cheap lamp and a 4watt compact fluorescent bulb - at least it will be cheaper. Alternatively, those Indiglo flat blue night lights cast a shocking amount of light for almost no energy cost. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [February 21, 2010, 9:36pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/4 "2010-02-21T21:36:44Z")
I turn off all my lights at night (except when I’m up). Between their amazing vision and their sense of smell, the cats have no trouble finding the litter box. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [February 21, 2010, 9:43pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/5 "2010-02-21T21:43:37Z")
Look at your cat’s pupils when it’s dim. Look at your pupils when it’s dim. Remember how much smaller the cat’s head is than yours. The cat can see just fine in the dark. ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [February 21, 2010, 10:39pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/6 "2010-02-21T22:39:57Z")
BTW, house cats are not actually nocturnal, but crepuscular (active both at dawn and dusk). Evidence from house cats shows that they can see in light one-sixth as bright as what we require. For one thing they have large eyes, which can gather in more light. However, it is the size of the pupil that actually determines the amount of light that enters the eye and hits the retina. Cats’ pupils can dilate and narrow like ours, but to a greater degree. With increased pupil size, the lens must also be larger to prevent distortion at the edge, and it and the cornea must be more strongly curved so that the light is focused most closely on the retina. The more strongly curved cornea creates a larger interiro chamber inside the eye. Another adaptation for night vision is a structure called the tapetum lucidum, which lies behind the retina. Like a mirror, the tapetum lucidum reflects the light that hits it back through the retina to produce a brighter image. (Basically, the same light gets used twice.) This is what causes the “eyeshine” you see when you catch a cat in your headlights, or at other times in dim light. (Source: _Cats, Smithsonian Answer Book_, John Seidensticker and Susan Lumpkin, Smithsonian Books, 2004) ---
**Author:** ![Beware\_of\_Doug](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)\ **Post date:** [February 21, 2010, 11:17pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/7 "2010-02-21T23:17:41Z")
Maybe mama just doesn’t want to risk stepping on kitty in a dark hallway. ---
**Author:** ![Nefarious\_Chipmunk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nefarious_chipmunk/32/1045_2.png) [@Nefarious\_Chipmunk](https://boards.straightdope.com/u/Nefarious_Chipmunk)\ **Post date:** [February 21, 2010, 11:25pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/8 "2010-02-21T23:25:54Z")
My cats roam around the house (and even play with each other) at night and I leave no lights on. We have stairs and furniture and they have to make their way to the garage to get to the litter box. I have never had a cat injury due to a cat running into something. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [February 22, 2010, 1:01am UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/9 "2010-02-22T01:01:03Z")
My experience matches what’s been presented: cats do just fine without artificial light. But the OP’s wife may not agree. So I think HelloAgain has the right compromise: get a couple of dim nightlights that consume a few cents per month of electricity. ---
**Author:** ![Markxxx](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@Markxxx](https://boards.straightdope.com/u/Markxxx)\ **Post date:** [February 22, 2010, 1:17am UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/10 "2010-02-22T01:17:09Z")
If you can see well enough in the dark to navigate your cat can can certainly see much better. Just get a nightlight as a compromise. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [February 22, 2010, 3:06am UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/11 "2010-02-22T03:06:23Z")
> [@Hello\_Again](#): > > Alternatively, those Indiglo flat blue night lights cast a shocking amount of light for almost no energy cost. I have one of those in the bathroom, but for my benefit, not the cats. They seem to do just fine with the moonlight/starlight/streetlight that filters in through the windows. Their main litterboxes are in the basement; they have no problem finding them. And they frequently hide/play underneath the beds, in a dark bedroom, with covers hanging down to the floor making it truly dark under there, and still they have no problem there. Cats can do just fine in what to us appears as completely dark. Suggest to your wife that one or two of these flat LCD/LED lights plugged into outlets at cat level in the hallway will be sufficient for the cats. And it will save a bit (a very little bit) on your electric bill. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 22, 2010, 2:10pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/12 "2010-02-22T14:10:15Z")
The [cat’s eye](http://en.wikipedia.org/wiki/Cat%27s_eye_%28road%29) was invented by Percy Shaw in 1934. Before that, cats kept bumping into things. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [February 22, 2010, 5:52pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/13 "2010-02-22T17:52:54Z")
My cats can have various races, battles, and general chaotic spaz-outs in the middle of the night with no help of a night light. No amount of light will help than find a piece of food on the floor once it has stopped moving. ---
**Author:** ![TerpBE](https://avatars.discourse-cdn.com/v4/letter/t/bc8723/32.png) [@TerpBE](https://boards.straightdope.com/u/TerpBE)\ **Post date:** [February 23, 2010, 5:24pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/14 "2010-02-23T17:24:13Z")
Get a LED nightlight. It will cost about 2 cents a month to operate. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [February 23, 2010, 5:41pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/15 "2010-02-23T17:41:02Z")
> [@barbitu8](#): > > BTW, house cats are not actually nocturnal, but \*\*crepuscular \*\*(active both at dawn and dusk). Nothing to add, but this is one of my favourite words. Dopers love fun words, so I thought to add a second use: [Crepuscular rays](http://en.wikipedia.org/wiki/Crepuscular_rays)are those visible beams of light that shine down through clouds and look like baby Jebus is being born all over the place. There are also anticrepuscular rays, but I won’t say what they’re pointing at. ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [February 23, 2010, 7:31pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/16 "2010-02-23T19:31:29Z")
OP, your poor cat is wondering why the hell it can’t get a decent dark night. 🙂 ---
**Author:** ![legalsnugs](https://avatars.discourse-cdn.com/v4/letter/l/45deac/32.png) [@legalsnugs](https://boards.straightdope.com/u/legalsnugs)\ **Post date:** [February 24, 2010, 1:42pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/17 "2010-02-24T13:42:33Z")
> [@FluffyBob](#): > > My cats can have various races, battles, and general chaotic spaz-outs in the middle of the night with no help of a night light. … Yeah, we get all kinds of this, too. When we turn out all the lights, it’s the starting gun that announces playtime begins NOW! And off they go! Doesn’t matter what time we go to bed - turning off the lights are the signal. Apparently our being out of bed inhibits them…:rolleyes: ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [February 24, 2010, 2:49pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/18 "2010-02-24T14:49:42Z")
> [@legalsnugs](#): > > Yeah, we get all kinds of this, too. When we turn out all the lights, it’s the starting gun that announces playtime begins NOW! And off they go! Doesn’t matter what time we go to bed - turning off the lights are the signal. Apparently our being out of bed inhibits them…:rolleyes: That’s because they’re crepuscular (I agree, it is a great word). If they’re indoor cats, “sunset” to them is whenever the lights go out. ---
**Author:** ![Snickers](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Snickers](https://boards.straightdope.com/u/Snickers)\ **Post date:** [February 24, 2010, 3:58pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/19 "2010-02-24T15:58:06Z")
Also, cats do have brains - I’d wager that they’ve memorized the layout of your house much in the same way you have. Haven’t you ever gotten up in the middle of the night for whatever reason and have navigated your house without turning on any lights? I certainly have. Couple their memory with their better night vision, and bingo bango. Cats don’t need night lights. ---
**Author:** ![cplif](https://avatars.discourse-cdn.com/v4/letter/c/48db29/32.png) [@cplif](https://boards.straightdope.com/u/cplif)\ **Post date:** [February 24, 2010, 8:19pm UTC](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904/20 "2010-02-24T20:19:59Z")
Having lived just about all my life with cats, I infer the following: - cats don’t like to be unconfortable, they pass their entire life mocking your intelligence, and settle down in the exact spot where they can 1 rest, and 2 survey all - try and stomp on your cat in the dark, if you (or your wife) can’t, the cat can see - if you still have qualms, try it for a week, if your cat still needs night lights, (I would change cats) try a led lamp [Next page](https://boards.straightdope.com/t/do-we-need-to-leave-the-lights-on-at-night-for-our-cat/529904.md?page=2)