IIT-K researchers study 'relaxed' brain activity to understand how stress impacts cognition

Researchers at IIT Kanpur are studying alpha waves in the brain to understand how stress affects cognitive functions and how individuals react differently to stress.

Researchers at the Indian Institute of Technology (IIT) Kanpur are studying alpha waves in the brain -- typically active when a person is awake and relaxed -- to understand how stress affects cognitive functions like attention, working memory, and risk-reward analysis.

''The essence of the study is to understand how different people react to stress differently and how stress can have a modulating effect on human cognition,'' Tushar Sandhan, associate professor of electrical engineering, told PTI.

The team aims to use non-invasive measures such as 'electroencephalogram' or EEG to build automated models of varied stress dimensions by correlating with factors, including feeling a loss of control or agency, helplessness and anxiety outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

Alpha waves in the brain, discovered about a hundred years ago, are said to be at play when one is in a relaxed wakeful state. They represent a calm, relaxed or meditating mind, typically with eyes closed.

Studies, such as one published in 'Institute of Electrical and Electronics Engineers (IEEE) Xplore' in October 2025, have explored mitigating stress by exposing a stressed individual to binaural beats in the alpha frequency range of 8-12 Hertz .

A binaural beat is an auditory illusion that the brain creates upon listening to slightly differing frequencies delivered to each ear separately.

The result showed a significant rise in alpha wave activity, which was corresponded with participants reporting lower perceived stress levels.

IIT-K researchers, led by Sandhan, are investigating the activity of alpha waves in the frontal lobe region, which is crucial for judgement, self-perception and decision-making, using an EEG.

The team is also studying 'frontal alpha symmetry' -- a biomarker referring to an asymmetry, where one hemisphere of the brain records more alpha waves compared to the other. Such asymmetry can exist in a strongly biased manner in specific psychiatric and neurological conditions, including depression.

''Frontal Alpha Asymmetry as a biomarker has been widely studied, especially in affective neuroscience and depression research,'' Sandhan explained.

''In many previous studies, depression has been linked to (a) greater left frontal alpha power, which could be interpreted as (a) reduced left frontal activity, which is associated with reduced approach motivation,'' he said.

Approach and withdrawal motivation are behaviours through which one either moves towards or 'approaches' a reward, or away from a threat (withdrawal).

The researchers are using a bioamplifier that is custom assembled with soft, flexible silicon electrodes of the EEG and a customised 3D printed ergonomic headband. Cardiac activity is also being collected via a smartwatch.

Sandhan and colleagues had previously proposed 'DAAFNet', an algorithm that analyses EEG data to identify and classify emotions. 'Affective computing' is an interdisciplinary research field spanning artificial intelligence (AI), psychology and cognitive science, and is focussed on developing systems that can recognise and interpret human emotions.

The systems so developed find uses in human-computer interface and brain-computer interface, designed to bridge the gap between human intent and machine action, and having wide-ranging applications from consumer electronics to medical rehabilitation.

However, even though alpha waves have been researched deeply for the past 100 years, according to an expert, data is still lacking on the nature of alpha waves as a biomarker, and more longitudinal studies on the matter are required.

According to Vaibhav Tripathi, assistant professor at the Indian Institute of Technology (IIT) Gandhinagar's cognitive and brain sciences department, alpha waves are the most prominent waves and become clearly visible as an alpha signature on an EEG system, when a person closes their eyes.

''But the issue here is that different brain oscillations or waves -- alpha, beta or gamma -- can associate with various cognitive functions or certain physiological responses, such as stress, where the oscillations can differ in an individual due to differences in mind states and traits.

''One's mental state changes throughout the day and also across days. In the morning, you will have more energy. You may then work on something and something can happen, or emotions can take a toll, or your mood goes off,'' he explained.

Tripathi, whose lab is studying alpha-wave signatures in individuals with attention-deficit/hyperactivity disorder (ADHD) and major depressive disorder, among other experiments, also talked about differences at the trait level -- whether someone is generally predisposed to happiness or tends toward depression or stress.

''Seeing that alpha waves or alpha rhythm could be associated with either some trait property or some state property, it's still a matter of debate as to the nature of information that alpha waves provide as a biomarker,'' he added.

He also suggested that stress is a variable phenomenon, and an objective measure of stress might be required.

''So, that's why these studies are challenging. We need an objective measure of stress so that it can account for aspects, such as state-level differences in alpha waves across a day and across multiple days,'' Tripathi said.