People engaged in work that involves heavy thinking, decision-making, problem-solving, and other processes taxing their mental faculties, could experience what doctors often refer to as ‘cognitive fatigue’. In layman terms this is usually described as being mentally exhausted, or more colorfully as being burned out or brain-fried. While signs of physical exhaustion are easily recognizable, such as limbs feeling heavy, eyes feeling droopy, and dropping energy levels, indications of mental fatigue are less easily discernible.
Nevertheless, there are several subtle signs of mental fatigue that you should be aware of, and take care to address, in order to ensure your mental health and wellbeing. Among these indications are, feeling overwhelmed or run down; being out of touch with your feelings and emotions; lacking interest or enthusiasm for things that you used to enjoy; stomachaches and digestive problems.
Other symptoms include head pain; changes in appetite; sleep problems, including disrupted sleep or fatigue; and increased cynicism, apathy, lack of motivation, and trouble focusing, as well as other changes in mood or emotions. If any or all of these signs sound familiar to what you are experiencing now, then you could be suffering from cognitive fatigue.
Researchers have for long been conducting studies to gain a better understanding of the mechanism behind cognitive fatigue. Now, a team of scientists in France, working in collaboration with colleagues in other universities around the world, say that the metabolite, glutamate, could be a major factor behind cognitive fatigue.
Metabolites are substances produced during metabolism (digestion or other bodily chemical processes) in the body. Glutamate is the most abundant metabolite in the brain, where it serves as a neurotransmitter, or chemical messenger, facilitating communication between brain cells.
For their study, the researchers asked participants to complete a series of tasks after which they were told to make various economic choices. The scientists then looked at the metabolites in participants’ brains using magnetic resonance spectroscopy (MRS), a type of medical imaging scan. The results revealed that tasks that were more cognitively demanding led to a buildup of glutamate in the lateral prefrontal cortex (LPFC) of the brain. The LPFC has been shown to be the part of the brain that plays an important role in several tasks, including: inhibition, paying attention, planning, problem-solving, working memory.
Researchers found that once glutamate accumulation occurs, it requires extra energy to activate the LPFC. In other words, after you have made a lot of choices — especially tough choices that take a lot of mental power — the brain requires progressively more energy to conduct its activities and this could result in the cognitive fatigue we experience. While it was not the main focus of their research, the scientists also found that glutamate concentrations decrease during sleep.
While this new neuro-metabolic theory of cognitive fatigue is interesting in its own right, the question remains: What can be done to safeguard the brain from becoming fatigued in the first place?
Below are a few suggestions to help you recharge and avoid future burnout. To begin, consider the mind-body connection. Previous studies have consistently shown the strong link between physical and mental health in ensuring an individual’s overall well-being.
Sleep: As shown by studies on LPFC, sleep is fundamental to lowering glutamate buildup, and getting enough sleep regularly is probably the best way to fight cognitive fatigue.Your body needs sleep even more than usual when you have a lot going on. Cutting back on sleep may seem like a good way to get more things done, but the more likely outcome is that you will feel exhausted and take longer to get things done.
Proper food: Whether it is mental or physical fatigue, exhaustion could make you turn to comforting or soothing foods, especially those that may have a lot of sugar, or empty calories. Instead, when you feel the need for a cognitive boost, try to make sure you get nutrients from high-fiber foods like oatmeal, beans, and nuts; protein-rich foods like yogurt, lean meats, eggs, and fatty fish; whole fruits and vegetables, especially blueberries, broccoli, and oranges; as well as whole grains.
Also, take care to stay hydrated and eat at regular times. You might feel like you are too busy to eat, but going hungry can lower your blood sugar and deprive you of cognitive energy.
Enough Exercise: A tired brain can sometimes benefit from a quick bout of refreshing exercise. It does not have to be strenuous exercises; any exercise has been found to be beneficial. If you can only manage a 15-minute walk on your lunch break, you are still benefiting by giving your brain a break. Sure, you could spend those 15 minutes getting more stuff done, but you will probably be able to work more efficiently if you give yourself a break.
Break down work: When you are already mentally exhausted, thinking about a big job you have to finish can seem too daunting for you to even make a start. Instead of letting thoughts of the entire project overwhelm you, try breaking the task down into smaller parts, and tackling each segment separately.
Avoid multi-tasking: We often bounce between multiple tasks in a one-hour block under the assumption that it improves our productivity. Instead, all it does is increase the buildup of glutamate that leads to cognitive fatigue, which could result in poor decision-making. It is important not to make critical decisions when feeling mentally fatigued.
Cognitive fatigue can also be relieved by mental relaxation, meditation, and mindfulness exercises. Besides the short-term consequences of impairing decision-making, increased glutamate levels in the brain have also been shown to impact long-term health. Excess glutamate is found to be excitotoxic, meaning that over the long term it can increase neurodegeneration or death of brain cells. Learning the skills needed to regulate your brain’s level of excitement is important for your long-term cognition.