Tired of being tired. Part II

Jun 6

Remember that feeling when you were excited to tackle an important project at work? Your motivation was super high and you dove in with laser focus, determined to make serious progress. But then, after a period of intense concentration and effort, you start to feel your energy fading. Your thoughts become foggy, your attention starts to drift, and that initial drive loses momentum.

It’s frustrating, but it’s also totally normal – we’ve all been there. Sustaining high levels of cognitive effort for extended periods inevitably lead to so-called functional fatigue, even for the most motivated among us (1). As a result, our ability to concentrate, remember information, and make decisions suffers (2). In this article, we’ll explore why this happens and what we can do about it.

Functional fatigue is another shade of tiredness

Functional mental fatigue is a state of mental exhaustion that results in a decreased ability to perform cognitive tasks efficiently (3).

This type of fatigue is different from motivational fatigue I wrote about earlier – the reward component isn’t involved here. Think about muscle failure after an intense workout. You’ve overused a muscle group, and you can’t do another rep. The same thing happens to your brain. You simply don’t feel like doing anything that requires mental effort – “My brain doesn’t work, I can’t think anymore,” – you might say.

In the gym, repeated stress on the same muscle leads to energy depletion and the buildup of metabolic byproducts like lactate. Your brain follows the same principle. When the same neural networks are repeatedly stimulated for an extended period, you face neural overload. Neurotransmitters deplete, metabolic waste accumulates, and energy stores run dry.

The impact of cognitive fatigue varies depending on the task and the individual. What one person finds demanding, is easy for another. Factors like cognitive abilities, prior experience, and current mental state all play a role.

Despite these individual differences, research shows that certain task characteristics consistently lead to higher cognitive demand and, consequently, more cognitive fatigue. These tasks often involve complex problem-solving, multitasking, or sustained attention. Some examples:

Designing a new workflow for a complex business process that has been causing delays and errors (problem-solving).
Reviewing a lengthy legal document to find specific clauses or inconsistencies (sustained attention).
Participating in a conference call while simultaneously taking notes and responding to urgent emails (multitasking).

So if it sounds like your job, there is a good reason to be tired.

What can we do about it?

No one likes feeling tired and incapable of quality thinking. So, can these episodes of functional fatigue and mental overload be avoided? According to the effort-recovery model (4), we can reverse accumulating strain by introducing recovery breaks into our work-day.

You already know this trick from exercising. You rarely go through a training session without breaks. So why do you sit in front of your computer all day long, hastily chewing your sandwich between Zoom calls?

It might feel like you’re saving time by skipping breaks. And perhaps that would be true if you were a factory worker. But in the world of knowledge work, the result is the opposite – the more you work non-stop, the less quality work you’ll get done over time (2).

So, taking breaks as common sense tells us, is backed by science. But what makes a good quality break? Despite this area being quite controversial due to multiple methodological factors, there are some tips you can rely on:

Focus on detachment from work during the break, not task-switching (5,6,7). Physical activity, breathing, meditating, or simply staring through the window will do.
Alternate breaks duration. During the workday, micro-breaks of less than 10 minutes can bring your energy back, reduce fatigue, and improve performance on routine or creative tasks. However, for cognitively demanding tasks, replenishing vigor with a short break may not be enough (8).
Don’t skip the lunch. That’s my favorite one. Longer lunch break spent outside of the workplace provides better detachment from work and therefore better recovery. As you might guess checking work emails during the break doesn’t count as “switching-off from work”. So better leave your phone at your desk (7,9)

Why fatigue?

Fatigue has an important biological meaning. It’s a sign that what we’re doing might not be worth the effort, and we should seek lower-effort strategies. Those who know how to conserve energy have a higher chance of survival.

Through fatigue, our body signals the importance of taking breaks and resting to reach big goals. Fatigue doesn’t stop us from aiming high; it reminds us to pay attention to our immediate needs, which ultimately helps us achieve long-term goals.

Don’t ignore fatigue; work smart, not just hard.