Some of us were lucky enough to start the week with a paid day off (thanks, Presidents!). We started the workweek on Tuesday, excited for a short week and expecting the days to fly by. And instead ... they ... dragged. 

Why does a shorter workweek after a day off often end up feeling longer than a normal week? While no psychology research has directly examined the phenomenon, some evidence suggests that it's because we humans are easily thrown by disruptions in our routines. 

"If I had to venture a guess, I would say that it could be because four-day work weeks are much less common and are a deviation from the typical five-day work week," Marc Buehner, a psychologist at the U.K.'s Cardiff University who has studied the psychology of time perception, said in an email. "There are some laboratory studies that show that predictable events are perceived as shorter than unpredictable events."

Buehner points to an idea explored in a 2007 study published in the journal PLOS One: In one experiment, researchers showed participants a series of 10 images, nine of the same image with one oddball image thrown in. (For instance, the volunteers saw nine repeat images of a shoe and one image of a digital clock.) Each image flashed on a screen for 500 milliseconds. After watching the series of images, the study participants were asked whether the oddball image was on screen longer or shorter than the repeat images. Each one of them incorrectly thought the oddball image was on screen longer. 

But it's not just about the weird image sticking out just because it's, you know, weird. The idea works with any kind of predictable routine. "So if I present you with a stream of numbers, say, 1 - 2 - 3 - 4 - 8 - 6 - 7, all with the same duration, the 8 would appear to have lasted longer than the other digits," Buehner explains. "One explanation why this happens is that perhaps the nervous system suppresses activation to predictable or familiar events. This would make evolutionary sense because it would exploit predictability to conserve resources."

This brings us back to the seemingly endless four-day workweek: It may feel longer because it screws with our weekday rituals.

"People might have certain routines that feel familiar to them," said Buehner. "They start the workweek on Monday with particular things -- a teacher might always teach the same class on Monday morning, for example. Now when they start on a Tuesday, the routine is different. Perhaps then this deviation from the standard of what is expected makes the week appear longer."

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