However, for everyone who's interested, there might also be a scientific explanation for why so many of us feel empty after coming home from the office.

A recent study that scanned people's brains at different points in their work day found that high-demand tasks that require intense, constant concentration can lead to a build-up of a potentially toxic chemical called glutamate.

Normally used to send signals from nerve cells, in large quantities glutamate alters the performance of a brain region involved in planning and decision-making, the lateral prefrontal cortex (lPFC).

The authors of the study divided their 40 participants into two groups and had both groups sit in an office in front of a computer for six and a half hours.

One group had to do challenging tasks that called on their working memory and constant attention.

For instance, letters were displayed on a computer screen every 1.6 seconds and participants had to sort them into vowels and consonants or, depending on the color of the letter, upper or lowercase.

The second group had similar but much simpler tasks. 

Interestingly, both groups managed an average 80% correct response rate.

But the researchers used magnetic resonance spectroscopy (MRS) to scan participants' brains and measure levels of metabolites.

The authors of the study took readings at the beginning, middle, and end of the day.

They discovered fatigue markers, such as increased glutamate concentration, but only in the high-demand group. (The build-up of toxic chemicals was only observed in the lateral prefrontal cortex and not the primary visual cortex.)

After the high and low-demand cognitive tasks, the two groups also had decision tests. This included choices about their willingness to ride a bike at different intensities, to perform harder or easier versions of cognitive control tasks, and how long they were willing to wait to receive a larger reward (the rewards themselves ranged from approximately $0.11 to $52.80 and the delays for receiving the reward ranged from immediate cash after the experiment or bank transfer after to one year).

In the end, the high-demand group preferred choices that were less taxing. These participants' pupils were less dilated (dilated pupils suggest arousal) and took less time to make decisions, which indicates they experienced this part of the experiment as undemanding.

So the study raises questions about the structure of our office routine. According to the results, we probably should break up tasks that need working memory and constant attention and take into account the fact that performance takes a hit.

"Science has shown ... that mental fatigue has real effects," Zoltán Molnár, a Professor of Developmental Neuroscience at the University of Oxford and Tamas Horvath, a Professor of Neurobiology and Ob/Gyn at Yale University, commented on the study.

Furthermore, they pointed out that we have plenty of similar examples. For example, after a long day in court, judges are more likely to deny parole (which is considered the safer option) and clinicians are more likely to prescribe unnecessary antibiotics at the end of a tiring clinical session.