What is stress?
Firstly, we need to define what exactly ‘stress’ is. James Humphrey defines stress (in his book: teenagers will be teenagers) as a factor that makes it difficult for people to maintain a state of homeostasis with their surroundings. This definition illuminates the increasing importance of managing stress, as the (western) world is more fast-paced and rapidly changing than ever before.
I was always under the impression that yoga was nothing more than the practice of postures for the benefit of flexibility – but it is so much more. What I always thought was the entirety of yoga is in fact just a subset: asana. Asana, derived from the sanskrit word for ‘seat’, related to the physical postures involved when practicing yoga. But yoga can also be practiced in the form of breathing exercises, referred to as ‘Pranayama’.
It’s no secret that people in all walks of life use yoga as a method to both stay supple and maintain a healthy mind – but do we have empirical evidence to support that such a practice can help us both physically and mentally? Well, it turns out we do.
Quantifying Mental States
Using an electroencephalogram (EEG), we can get an understanding of activity in the brain. This activity can be categorised into five ‘bands’, and it is the interplay of these five bands that can help us understand different states of consciousness. Below are the five different brainwave bands, and what insights we can gain from their heightened activity.
Alpha (8-13 Hz)
Associated with focused attention and relaxed wakefulness; increased Alpha wave activity is associated with a relaxed, but alert, state.
Beta (12-30 Hz)
Associated with active attention and problem-solving. As the beta frequency is associated with alertness, attention and cognitive processing, several studies have attributed increased Beta activity to mental stress.
Gamma (30-50 Hz)
Associated with high-level cognitive functions such as learning and memory. Gamma waves are observed when the brain is actively engaged in complex tasks. In stressful situations, one typically observes increased gamma activity, attributed to the brain’s adaptive response to a circumstance that is seen as demanding or challenging.
Delta (0.1-4 Hz)
Associated with deep sleep, unconscious processing and memory consolidation. Delta waves dominate during deep sleep, when the body and mind are in their most restful state. As Delta waves are closely related to deep, restorative sleep, they are thought to be closely related to immune system health and physical healing
Theta (4-8 Hz)
Associated with relaxed wakefulness and daydreaming, and are linked to the subconscious mind. Theta waves are dominant during light sleep, meditation and deep relaxation and are used in memory consolidation and often involved in learning.
The Results
A study was conducted to show how brain activity changes during the practice of Yoga, characterised by relative changes to the above brainwave bands. What was found was a staggering 19.31% increase in Delta activity, accompanied by a 15.4% increase in alpha activity and an 18.68% increase in Gamma activity.
So what does this tell us? The details in this study give us a window into the mental states promoted by a continued practice of yoga-based stress management programs. Increased delta activity shows us that such practices can help achieve a deeply relaxed, restorative state. Increased alpha activity highlights that while one may be in a relaxed state, they are alert and focused – something which is also reinforced by increased gamma activity.
Conventionally, heightened states of alertness can be associated with heightened states of stress. But what this study shows is that there is a way to offer heightened states of alertness while providing a state of relaxation – a powerful combination.
Conclusion
In a data-driven world, we often find ourselves relying more on numbers than anecdotal or experiential evidence. What we have seen here is that we can be assured that what we read about yoga’s effect on our mental states is supported by the numbers, and the results of yoga-based practices can yield a potent combination of focus and relaxation.
