Why does thinking too hard make you tired?

Ever spent the day doing nothing, just mulling over a difficult decision? Did you crawl into bed that night exhausted and drained, even though you left the couch only to pee?

Thinking hard can actually make you tired because it requires a lot of mental effort, which can be draining. When you are thinking deeply about something, your brain is working hard to process and analyze information, and this can be mentally exhausting.

What is brain fatigue?

Brain fatigue, also known as mental fatigue or cognitive fatigue, is a feeling of mental exhaustion or tiredness that can occur after extended periods of mental effort or concentration.

It’s thought to be caused by changes in brain physiology, such as an increase in the signalling molecule glutamate. When we perform difficult tasks, glutamate levels increase in the brain which may lead to feelings of tiredness.

The prefrontal cortex plays an important role in cognitive control, such as decision-making and focusing on tasks. When we spend prolonged periods engaging in mentally taxing activities, the neurotransmitter glutamate builds up in this area of the brain.

High levels of glutamate

Glutamate is a neurotransmitter that plays a key role in brain function, including learning and memory. It’s involved in the transmission of signals between neurons and is essential for normal brain activity.

Excessive levels of glutamate can cause overstimulation of neurons and lead to the release of other neurotransmitters, such as dopamine and norepinephrine. This can result in feelings of stress and anxiety, as well as physical symptoms such as muscle tension and difficulty sleeping. Over time, high levels of glutamate can lead to brain fatigue and other negative effects on brain function.

Glucose depletion

The brain requires a large amount of energy to function, which it gets from glucose. When the neurons in the brain fire, they absorb extra oxygen and glucose from nearby capillaries. Therefore, when performing a difficult mental task, more glucose is burned than usual.

This results in less glucose available for other parts of the body, leading to feelings of physical exhaustion.

Other brain metabolites responsible for fatigue

Other brain metabolites responsible for fatigue include glutamine, gamma-aminobutyric acid (GABA), monoamines such as norepinephrine and serotonin, and adenosine.

When a person spends prolonged periods of time engaged in mentally demanding tasks, the brain can experience changes in metabolism that lead to feelings of tiredness.

How to use your brain so you don’t get brain fatigue

There are several strategies that you can use to help avoid brain fatigue while thinking:

Recognize when cognitive fatigue is occurring

Cognitive fatigue can be identified by a decrease in mental energy and focus, as well as an increase in irritability and frustration.

Take a mental break

Take breaks during long periods of concentrated thinking to help rejuvenate your brain. These breaks should involve doing a different activity that requires effort, but not task switching (multi-tasking) that worsens fatigue.

Rest during your breaks instead of surfing the internet or looking at your phone while taking them. Certain activities, such as meditation and yoga, have been shown to help reduce glutamate levels and promote relaxation.

During periods of rest, such as during sleep, the brain’s activity levels decrease and glutamate levels can be naturally reduced. This can help to promote feelings of relaxation and restore balance to the brain’s neurotransmitter systems.

Avoid multi-tasking

Avoid task switching (multi-tasking) as much as possible to prevent further wear on your brain’s resources . Block off chunks of time for single activities , then take short mental breaks between them before engaging in new tasks.

How to improve your brain stamina

Other things you can do to improve your brain stamina so you can think harder for longer:

Good quality sleep

Get enough restful sleep each night to help reduce glutamate concentrations and restore mental energy levels for tomorrow’s tasks.

Stay hydrated

Dehydration can affect cognitive function and lead to brain fatigue, so it is important to stay hydrated by drinking plenty of water.

Exercise regularly

Regular physical activity can help to improve blood flow to the brain and increase oxygen levels, which can help to reduce brain fatigue.

Eat a healthy diet

A healthy diet that includes a variety of nutrients can help to support brain function and reduce the risk of brain fatigue.

Manage stress

Chronic stress and anxiety can take a toll on the brain and lead to brain fatigue. Finding ways to manage stress, such as through relaxation techniques or therapy, can help to reduce the risk of brain fatigue.

Don’t take on too much

Before you say yes to yet another project, ask yourself if you are actually physically and mentally capable of doing it well. The last thing you need is another unfinished project burdening you.

By following these strategies, you can help to reduce the risk of brain fatigue even if you have to use your brain lots.