For some students, the hardest part of an exam is not the material. It is sitting down, looking at the first question and suddenly wondering why none of the information they studied seems to be there.

The nervous feeling before an exam is commonly known as “Test Anxiety.” And it can involve much more than simply feeling worried. A racing heart, sweaty hands, difficulty concentrating and constantly thinking about getting a bad grade can all be part of the experience.

But what is actually happening in the brain when an exam makes us nervous?

One explanation starts with the brain’s response to stress. When we perceive something as threatening, the body activates its stress response, releasing hormones and neurotransmitters that prepare us to respond. This system can be useful when facing an actual physical danger, but an upcoming chemistry exam can trigger some of the same biological responses.

The brain’s prefrontal cortex, which is involved in attention, decision-making and working memory, is particularly sensitive to stress. Neuroscientist Amy Arnsten wrote in “Nature Reviews Neuroscience” that the prefrontal cortex “subserves our highest-order cognitive abilities,” but is also especially sensitive to the effects of stress.

That matters during an exam because working memory is what allows us to temporarily hold and manipulate information. It is the mental space we use when solving a math problem, remembering the beginning of a question while reading the rest or keeping track of several steps in a chemistry calculation.

Under high levels of stress, that system can become harder to use. Research has found that stress can affect the neural systems that support working memory. A study examining acute stress and prefrontal working memory found that stress increases cortisol levels and alters prefrontal cortex activity; however, the behavioral effects depended on the specific conditions of the task.

When Worry Takes Up Brain Space

Stress is only part of the problem. For students with test anxiety, worry itself can compete for attention.

Imagine sitting in an exam thinking, “What if I fail? What if I get a C? Everyone else is already on question five. Oh, I should’ve studied more.” None of those thoughts help answer the question in front of you, but they still take mental resources.

Researchers have studied this idea through processing efficiency theory and attentional control theory. The basic idea is that anxiety can interfere with the brain’s ability to direct attention toward the task. Instead of using all available resources to solve a problem, some of that attention is occupied by worry.

Psychologist Michael Eysenck and colleagues described this relationship by explaining that anxiety can “impair efficient functioning of the goal-directed attentional system.”

This may help explain why a student can understand something while studying but struggle to recall it under pressure.

It does not necessarily mean the information disappeared from memory. Instead, anxiety may make it harder to direct attention and working memory toward retrieving and using that information.

The Amygdala and the Stress Response

Another important part of the brain’s stress response is the amygdala, a region involved in processing emotionally significant information and detecting potential threats.

The amygdala does not simply make us afraid. It communicates with other brain regions and helps coordinate the body’s response to stressful or emotionally important events.

Research on stress and memory shows that interactions between the amygdala, hippocampus and prefrontal cortex can influence memory. A review published in Nature Reviews Neuroscience found that stress can strengthen some emotionally significant memories while impairing aspects of memory retrieval and working memory.

This may help explain the frustrating experience of walking out of an exam and suddenly remembering the answer to a question you could not answer five minutes earlier.

The information may have still been stored. The problem was accessing it under the exam conditions.

Does anxiety always make us perform worse?

Not necessarily. The relationship between anxiety and performance is more complicated than simply saying that nervous students will perform poorly. Some students may compensate for anxiety by putting in more effort and concentrating harder.

In fact, a 2026 study published in Biological Psychology found that students with higher test anxiety did not necessarily perform worse on a working-memory updating task. However, researchers observed differences in their brain activity, suggesting that students with higher anxiety may have been using additional cognitive effort to maintain their performance.

The researcher found that when task demands increased, this compensation became less effective.

This distinction is important. Someone can perform normally while still using more mental effort to do so.

So, how much does test anxiety matter?

Research consistently finds a relationship between test anxiety and academic performance, although the size of that relationship varies. A 2018 meta-analysis combined results from 238 studies and found that test anxiety was negatively associated with several educational outcomes, including GPA and standardized and university entrance exams. The researchers also found that perceived difficulty and the consequences of an exam were associated with higher test anxiety.

A separate meta-analysis focusing on university students examined 44 randomized controlled trials involving 2,209 students. The researchers found that interventions reduced test anxiety and were also associated with improvements in academic performance, although they noted limitations in the quality and consistency of the available studies.

So while feeling nervous before an exam is normal, intense test anxiety can become more than just a few butterflies.

The next time your mind suddenly goes blank during an exam, it may not mean you did not study enough or that you somehow forgot everything you knew.

Your brain may simply be trying to do two things at once: answer the question in front of you and manage the stress surrounding it.

And when an exam feels like a threat, the brain systems designed to help you think clearly may also be trying to protect you from the threat, even if you don’t want it to.