If you’ve picked up a book by Oliver Sacks or read practically any article about neuroscience, you’ve probably heard the word “synaesthesia” bandied about. In case you haven’t, it’s the phenomenon of sensory responses arising from unexpected sources. Like seeing colors when you hear numbers, or smelling cabbage when you pet a cat.

Besides providing people with another way to feel special about themselves, synaesthesia has shed some light on the anatomy of the brain, by showing us that signals from outside stimuli can “overflow” into neighboring brain regions responsible for un-related perceptions.

For me, the days of the week have always been associated with certain colors, and those colors map to certain numbers. One time in middle school, I woke up and looked at my clock, (it was one of those with the big white flip-numbers) and I read it as 7:04 which, in my head, translated to a bright Tuesday yellow. That meant I had to get up and go to school. So I took a shower, got my lunch ready and walked to the bus stop. The winter mornings in Michigan are quite dark, but for some reason, this one was darker than usual. As I stood there in my snow boots, waiting for the bus, or any of my schoolmates to arrive, I began to wonder what time it was. I had no watch, and the only memory I had of my alarm clock was a flash of yellow. I knew something was wrong, so I went back home to see that I had actually woken up at 4AM – probably 4:07 or some other number combination that elicited the same yellow.

I wouldn’t say I have a serious case of synaethesia (that was the only time it had any direct effect on my life) but it’s strong enough that I could make the illustration above without spending more than a few seconds in the color picker.

Besides being mapped to colors, the days of the week each have specific feelings that accompany them.

• Sunday is calm and glowing.
• On Monday, the week is a great big green balloon filled with possibility.
• Tuesday is the brightest of all days – when there’s still plenty of time to start on all those ambitions that looked so grand on Monday. (If you want to run a new idea by me, talk to me on a Tuesday. I’ll tell you how great it is.)
• Wednesday is the dramatic crescendo of the week, when things either come together or they don’t. It’s the violent, bloody collision between the week’s beginning and end. If the current epoch of the Earth were to be assigned to a day for some reason, it would be Wednesday.
• Thursday is a down and dirty day. A chocolate bar that begs to be eaten.
• Friday is another bright one. A vivid yellow like the sun on the beach. Is it because the word sounds like “fried egg” and I’m picturing the yolk?
• Saturday is like a whale swimming underwater at midnight.

I suspect the feelings associated with the days have more to do with their placement within the week, but the feeling often relates to the color. It makes me think that concept, metaphor, sensation – basically all the cognitive tools of art, and every method the brain uses to create meaning out of nonsense – these things occupy a relatively close-knit neighborhood in the brain – a neighborhood with fences that are easy to hop and buses that run all night.