New Delhi, Oct. 19 -- It's a quiet Tuesday evening inside the Blue Tokai Coffee Roasters cafe in Koramangala, Bengaluru. The aroma of freshly brewed coffee hangs in the air as I'm handed a device that looks fairly simple, black in colour and something between a headband and a headset, except it doesn't cover the ears. There are no flashy screens, no blinking lights, no music to play. It isn't built to count your steps or track your sleep. Instead, it goes a step ahead and is aimed at speaking to your brain.

"This might feel like a slight tingling," says Jai Sharma, co-founder of Mave Health, a Bengaluru-based mental wellness startup, as he connects the headset to an app on his phone. He taps a button on his phone. A few seconds later, I ...