The real mental fatigue culprit
Your brain is actually quite good at energy management
Most of us are familiar with “brain fog”, or have experienced that feeling of your mind being completely fried. Perhaps it occurred after studying long hours for an exam or spending a day in deep work. Mental fatigue feels real, but the reason for it doesn’t have to do with energy depletion. We’ll get to that later. It’s relevant to note that we don’t tend to mental fatigue as readily as physical fatigue. It is a solid argument, however, that we’re not necessarily great at preventing any type of fatigue in this hustle culture we’re living in. But, I digress.
Our brain is the command center for our body and uses 20% of our body’s energy. Of that energy expenditure, 25% is used to maintain the brain’s integrity (e.g. preserve cell walls) and 75% is used for information processing. It’s energetically expensive to keep our human computer in peak condition. So, what is mental energy? Mental energy refers to our capacity to perform cognitive functions, such as concentrating, problem-solving, directing our attention appropriately, and deciding what to have for dinner (is this a daily challenge in anyone else’s house?). When our brain has been tasked with a lot of computation, we may experience decision fatigue, have a hard time focusing, or feel overstimulated.
As is the case with our physical energy, our mental energy seems to increase and decrease throughout the day. One of the contributors to feeling mentally exhausted is based on a defining characteristic of the brain. When faced with a challenge, the brain prefers the path of least resistance. The intention is to conserve energy. But, of course, that most often results in procrastination, which only adds to our cognitive load.
Here’s what’s interesting: Mental fatigue isn’t actually due to energy depletion. Research has demonstrated that the brain is, in fact, quite good at managing its own energy. When one area of the brain is more active than usual and utilizes more energy, other areas of the brain utilize less energy. So, while there may be a slight change in energy consumption when a particular brain region is processing a lot of information, it is offset by decreased energy demands in other parts of the brain.
The real culprit of our mental energy challenge is stress. You may have noticed that when you’re extremely stressed, you can’t make decisions. Even the smallest choice, like what to wear, can feel incredibly overwhelming. So in order to experience less mental fatigue, you need to manage your stress levels. And, as is the case with anything that has a battery, you want to refuel (i.e. rest) when the tank is ¼ full instead of waiting until you hit empty.
Before I offer a few suggestions, reflect on how you typically refuel - and when. Do you wait until you’re hangry or the headache kicks in before you grab a snack? Do you ever realize that the last 30 minutes of work were entirely unproductive? Do you serve your family until you feel impatient and irritable? When you finally zoom out and decide to make a shift, what do you do? Do you go outside for a short walk, take a few deep breaths, or maybe even close your eyes for a few minutes
Mental energy management is critical to get the most out of your days, but also to fully reset. Here are a few ways to replenish your reserves:
Move your body
You know I preach movement. The science-backed, brain-boosting benefits of movement are just impossible to deny. Anchor your day (or your mind) with at least 30 minutes of movement in the morning, afternoon, or evening. But also, set your alarm for “movement snacks” (think: 2-5 minutes of squats, walking, sun salutations) throughout the day.
Sit in silence
The opposite of movement has also been proven to increase focus, boost mood, and improve reaction time. Even 1 minute of closing your eyes and observing your breath, with zero outside stimulation, can do wonders for your mental energy.
Practice alternate nostril breathing
This breathing technique has been shown to improve cognitive function. When you need an injection of mental clarity, close your eyes and practice ten rounds of this.
Unitask
Technically, the brain cannot actually multitask. Rather, it switches rapidly between mental tasks, which is detrimental to productivity and drains mental energy. So, focus on one task at a time until it’s complete or you take a break.
Schedule breaks
Deep work (focusing on one thing for a period of time increases your chance of getting into a flow state) is incredibly beneficial for the brain. But, it’s also important to force yourself to step away from the work at least once every 90 minutes. Do something that works your brain in a completely different way.
Rest
Dial in your sleep hygiene at night and give yourself permission to rest, ideally before your body forces you to (e.g. through illness, injury, or burnout).
Peak performance requires mental and physical energy, so prioritize refueling and remember to rest before you run on empty.
