New Delhi, 24 Sept

Brain scans have revealed possible neural activity that could help one feel relaxed while performing yoga nidra or 'yogic sleep' -- a meditation technique that induces a sleep-like state whilst maintaining heightened awareness, according to a study.

A team, including researchers from IIT-Delhi, conducted functional magnetic resonance imaging (fMRI) of the brain of 30 experienced and 31 novice meditators.

They looked at the participants' default mode network, which is the brain's "background mode," known to be at play when one is being introspective, or just letting their mind wander.

On comparing the results, the researchers found a reduced connectivity in the default mode network of the experienced meditators the entire time they practiced yoga nidra, compared to their resting state, which could indicate that they are "being more in the present."

The default mode network is generally associated with thinking about the past or the future, autobiographical processes, thinking about others, scene construction and even goal directed cognition, explained study author Sonika Thakral, an associate professor in the department of computer science, Shaheed Sukhdev College of Business Studies, University of Delhi.

"During meditation in healthy participants, a drop in within-network default mode network connectivity would signify reduced processes associated with mind wandering or thinking about past or the future and being more in the present moment," Thakral told PTI.

"Our findings highlight a significant reduction in default mode network functional connectivity among meditators compared to novices across all stages of yoga nidra," the authors wrote in the study published in the journal Scientific Reports.

These changes in brain activity were more noticeable in the experienced meditators, which could indicate that they have reduced mind-wandering, compared to the novices, the authors said.

The yogic sleep practice is usually attempted in Shavasana, or a supine position resembling the stillness of a corpse, accompanied by audio instructions to help guide the individual's awareness to different parts of the body.

"According to yogic texts, yoga nidra helps bring the 'samskaras' buried in deep subconscious minds to the surface and eventually helps release them, thereby promoting health," lead author Rahul Garg, a professor at IIT Delhi, said.

Thakral explained that samskaras are patterns of thoughts and subsequent actions.

"The way our brain is connected stores a lot of these patterns resulting in a set of repeated thoughts and actions. One's emotions, belief systems, reactions and thoughts buried in deeper levels of consciousness go hand in hand and influence each other," she said.

She added that the default mode network functions by retrieving episodes from the memory and is also associated with emotion.

"Meditation reduces the activity within the default mode network and allows one to weaken the strength of these samskaras or impressions, thereby resulting in the ability to have a better say over our thoughts, habits and actions," Thakral said.

The results provide a scientific basis for the relaxing effects of yoga nidra, which could potentially inform mental health treatment by including the practice in stress management and cognitive therapy, the team said.

Further, as the participants listened to the guided instructions, the researchers observed activation in the thalamus -- involved in controlling consciousness and sleep -- and the brain regions known to play a role in processing emotions.

"The activation of brain areas involved in processing emotions is a very interesting finding in this context. This may explain why it has been found effective in anxiety in certain studies," Garg said.

This study is the first to subject yoga nidra to the scrutiny of FMRI, according to the authors. -PTI