Guessing it's NOT a northern exposure. Sunlight strips chroma or in other words is washes color out.

In order to stand up to abundant light, there has to be some color in your paint color.

Going from day perception to night perception shouldn't be that big of a deal because of this thing called chromatic adaptation.

Over time, you learn or rehearse a specific color. Take a banana for example. Bananas are banana yellow no matter what the light source. It's yellow in the kitchen in the day time *same as* it's yellow in the dining room at night.

Because we've learned what banana yellow *is*. Bananas have been a constant in our color experience and no matter what degree of color acuity one may have, everyone can identify a banana as what they know to be yellow. (color vision impaired notwithstanding)

Your wall color should *adapt* in the same manner given a short period of time. (actually you're the one that adapts)

What your describing isn't the typical issue of color constancy - meaning it looks one way under one light source and then changes in color characteristic - like shifts from yellow to a sickly yellow-green. (an argument for metamerism is in this mix too)

What you're descrbing is a shift down/up in chromatic value. And I would suggest that is something that would correct itself provided the paint color is chosen to meet your expectations in the natural light source, not the artificial.

I don't agree that you will read the color about the same. Maybe if you aren't picky or OCD about color to begin with ... but if you are posting here good chance you will perceive the color difference and it will drive you crazy! I used BM Manchester Tan and had to repaint after a month. Open concept with light from different directions and 2 large skylights. It only looked like the photos I had seen on one wall. The rest of the wall/rooms looked gold/green and it turned sickly green at night. Yuck!

I repainted with BM Grant Beige and it looks good the majority of the time. Only one wall turns a bit too sagey green at night, but not a bad color. I tested about 15 quarts to get the right color and still had to repaint! Good luck :-)

I've never noticed the green washed out during the daytime until recently, when I started trying to decide on a color for my living room.

That's exactly how it works/happens.

Southern, western, and southwestern exposures notoriously have the most robust natural light exposures. And the stripping of chroma or colorfulness can be extreme.

You can't hinge color selection 100% on artificial lighting because you can adjust and control the lighting plan - like change the *color* of the bulbs, add more lamps, install a dimmer, etc.

But you can't spin your house so the windows face a different direction. So, you always go by natural daylight, between the hours of 10 am and 2 pm is best, partly cloudy day. (because that's the closest conditions you can get to an average quality of daylight.)

Again, it's not the finer nuances of paint color that you're describing, noticing and feeling. It's more literal than that. You can experience "x" amount of color in one quantity and quality of light vs. "x" amount of color in another. And chromatic adaptation is our natural means of balancing that perception so we can function.

Imagine what it would be like if the vision system didn't work that way? We'd only be able to detect the perfect ripeness of our bananas between 10 am and 2 pm on partly cloudy days. What PITA. :~D

Funcolors

Do you think though, if you aren't using the room between 10 and 2 that maybe you should skew the colors to how it's artifically lit? I've seen some bedrooms in particular that look okay during the day with the lights out but they don't look so great in the evening/night -- partly because of the lighting.

This is an extreme example but when the Drawing Room at Lansdowne House was first restored from its ivory and palest pastel version to the true paint analysis version, and lit like most rooms at the museum, the people who paid for it had a fit. This is how you see the room now, which is probably still lit a bit more than it would've been when in use originally, it was mostly used when it was dusk or dark outside:

Sure, can if you want to.

Usually if you like a wall color when it's lit by the peak, most robust light quality the space has to offer, odds are it will remain pleasing as the quality of light changes throughout the day/evening.

Can always switch up the lighting plan and change light bulbs, etc. Again, it's not nearly as easy to change or add fenestration.

Color changes all day, every day. Eventually, any hyper-sensitivity to the dramatic swings in chromatic up/down quality fades as we grow accustom to the color in the environment. Have to draw the line somewhere and identify some point of criteria to make a decision. Because the wall color is not going to be consistent, not going to look the same at all times.

And a good average guideline is that 10 - 2 business. But it's just a guideline. Not a rule.

Again, this isn't about perceived color characteristics changing like a pretty buttercream yellow transformed by lights at night into a skunky yellow-green. The OP's question was about chromatic value shifts up/down.