Understanding Mental Fatigue in 2022

Arguably, we’ve got more to think about than ever. Climate change, insane housing costs, the ongoing risk of COVID-19, political corruption, the threat of war… There are few people who don’t find at least one of these things more than a little stressful. And while social media helps to keep us in the loop, having the latest news right at our fingertips, 24 hours a day, doesn’t always provide comfort or reassurance. 

To make things worse, a new study, published in Current Biology, has found that thinking about all of the above (and then some) can make us even more tired, accelerating the path to total mental burnout.

“Nobody knows what mental fatigue is, how it is generated, and why we feel it,” says the first author of the study Antonius Wiehler, of Pitié-Salpêtrière University Hospital in Paris, France. “It has remained a mystery despite more than a century of scientific research.”

While machines can do cognitive tasks continuously without fatigue, the brain is different and Wiehler and his colleagues wanted to understand the how and why. “Mental fatigue has important consequences: for economic decisions, for management at work, for education at school, for clinical cure, etc.,” he adds.

A Closer Look at the Study 

When intense cognitive work is prolonged for several hours, some potentially toxic by-products of neural activity accumulate in the part of the brain known as the prefrontal cortex.

“This alters a person’s control over decisions, which are shifted towards low-cost actions (no effort, no wait), as cognitive fatigue emerges,” explains Wiehler. He adds that they are talking about mental exhaustion here and not merely drowsiness.

Wiehler and his team employed a new technique to measure the diffusion of brain substances with magnetic resonance spectroscopy. “It was particularly useful, in our case, to show that glutamate accumulates in synapses (outside neurons), where diffusion is faster than in cellular compartments (inside neurons),” he says. 

The researchers hope the study will help people understand mental fatigue a little better. “Influential theories suggest that fatigue is a sort of illusion cooked by the brain to make us stop whatever we are doing and turn to a more gratifying activity,” Wiehler says. “But our findings show that cognitive work results in a true functional alteration (i.e. the accumulation of noxious substances), so fatigue would indeed be a signal that makes us stop working, but for a different purpose—preserving the integrity of brain functioning.” 

What Is Mental Burnout? 

It helps to understand the biological reasons why thinking hard makes us tired, but it’s also crucial to understand the many forms that mental burnout can take. 

“When people are under prolonged stress they can end up feeling overwhelmed and emotionally drained and this can eventually lead to a breakdown, mentally and/or physically.  This is often referred to as burnout,” says Zishan Khan, MD, a child, adolescent, and adult psychiatrist with Mindpath Health. 

Burnout can have many signs and symptoms, and is sometimes confused with regular feelings of stress, but the difference is the extent and severity of what is experienced, Dr. Khan explains. 

“People experiencing burnout often feel helpless when it comes to emotionally being able to deal emotionally with problems in their lives,” he says. “They become overly tired and feel zapped of all energy.”  

Some even develop physical complaints, such as musculoskeletal pain, abdominal discomfort, or bowel issues. Other symptoms include self-isolation, negative thinking, and irritability around others, often combined with extreme frustration and a short fuse.

“Many people display little to no enthusiasm in any part of their daily life, and often complain of feeling numb,” says Dr. Khan. “Burnout can also make it hard to concentrate, complete even simple tasks, and be able to manage everyday responsibilities. If left unchecked, burnout can progress further to depression.”

Avoiding—or Reducing—Mental Burnout

Mental fatigue can build up over time, and prolonged and overwhelming tension isn't healthy for anyone. "Stress can be dangerous and lead to very serious consequences if not properly managed," warns Dr. Khan.

His top tip? Make sure you're getting enough shut-eye. "Proper sleep will greatly help relieve mental fatigue, help recharge your body, and prevent escalation to burnout or a complete breakdown."

Taking frequent breaks during the day is crucial as well, especially when you are taking part in stressful activities. It can be helpful to set aside time for yoga, meditation, or taking part in an activity that you find relaxing. And, of course, a healthy diet and exercise isn't just good for your body— it can work wonders when it comes to easing mental fatigue.

"Additionally, it can be beneficial to identify what the particular source of stress is so that appropriate steps can be taken to lessen the pressure," Dr. Khan adds. For instance, if your job is leading to mental fatigue, then taking some paid time off to go on a vacation or just resting and unwinding at home can greatly reduce the likelihood of burnout.

Finally, Dr. Khan recommends seeking help from a friend, loved one, or a professional if you believe you may be experiencing more serious symptoms of depression and anxiety, such as avoiding social activities, despair and guilt, feelings of hopelessness, irrational fears, or thoughts of suicide.