Google CEO Sundar Pichai says he uses NSDR, or 'non-sleep deep rest,' to unwind. Here's what it is and how it works.

• Google CEO Sundar Pichai recently told the Wall Street Journal he uses non-sleep deep rest, or NSDR, to relax.
• NSDR involves "self-inducing a state of calm" and "directing our focus to something." It can help with sleep, stress, anxiety, relaxation, and even learning.

Plenty of CEOs swear by meditation, but Google's chief executive likes to relax using a slightly lesser-known practice.

In an interview with The Wall Street Journal this week, Sundar Pichai said he sometimes unwinds with the help of something called non-sleep deep rest, or NSDR, a term coined by Stanford neuroscience professor Andrew Huberman, who says it involves "self-inducing a state of calm" and "directing our focus to something."

"I found these podcasts which are non-sleep deep rest, or NSDRs," Pichai told the Journal. "So while I find it difficult to meditate, I can go to YouTube, find an NSDR video. They're available in 10, 20, or 30 minutes, so I do that occasionally."

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According to Huberman, NSDR can help people relax, fall asleep more easily, reduce stress and anxiety, ease pain, and even accelerate learning. It's commonly achieved through two of what Huberman calls NSDR "protocols": yoga nidra and hypnosis.

The former involves lying flat on your back on the ground, typically with your eyes closed, and following guidance from an instructor, virtually or in-person, as they lead you through a number of activities, yoga nidra instructor Tracee Stanley told Insider.

In yoga nidra, you may be asked to scan for places of tension, focus on your breathing, bring your awareness to various parts of the body, or begin diaphragmatic breathing, all with the intention of "giving the mind something to focus on," Stanley says.

As your body begins to rest, doing these things can cause your heart rate to slow down. Your brain may also switch from beta waves, which are associated with an active mind, to alpha waves, which correspond to a more relaxed brain state.

Stanley says people doing yoga nidra may find themselves "hovering in a liminal space between being awake and falling asleep." Their bodies may physically fall asleep, yet they "maintain awareness both internally and simultaneously being aware of their surroundings."

Stanley added that the body becomes "more receptive to inertia" during yoga nidra, which she notes is different from meditation because it is a form of "non-doing."

"You're allowing inertia to let your body rest and be held by whatever it is that you are supported by," she said. "That means your body for once can actually release needing to do anything."

As for hypnosis, Huberman describes it as "a state of calm and high focus." Hypnosis can be done with the help of a clinical hypnotist, or it can be self-induced using various hypnosis apps or videos.

"It's like looking at something through a telephoto lens," he said. "You're eliminating the surround. So it's a state of high focus, which normally ... would be associated with a high degree of excitement or stress. But hypnosis is a unique state, because you have a high degree of focus, but you're very relaxed."