The word "awesome", it's fair to say, has become devalued through overuse. Recently, I was sitting in the press section at a political event when a young official approached and said if I didn't mind switching seats, "that would be awesome". (This was in the US, admittedly, where the overuse is extreme.) I switched. "That's awesome," he responded. I overheard him use the word several more times. I realise it's possible he was an endearingly unjaded chap, perpetually astonished by the human capacity for doing things such as moving from one chair to another. But I doubt it.

Real awe is harder to come by. Most of us lead "awe-deficient" lives, according to the neuropsychologist Paul Pearsall, who died last year and who argued that awe should be considered "the 11th emotion", in addition to the 10 recognised by researchers. If we don't realise we lack awe, perhaps that's because we understand it so little: even Pearsall struggled to define its strange mix of fascination and fright, which can be invoked by a landscape or a newborn baby, but also by a natural disaster or a cancer diagnosis. "The best description I've been able to give it so far is that - no matter how good or bad our brain considers whatever is happening to be - it is feeling more completely alive than we thought possible before we were in awe," he writes in his last book, Awe, which begins with the story of the near-death in infancy of his son. He'd never been unhappier than while waiting to learn if his son would survive. But, "at the same time, I have never felt such profound awe".

The centrepiece of Pearsall's research was The Study Of The Awe-Inspired, a mammoth investigation of people who felt awe regularly. Living a more awe-filled life, Pearsall concluded, wasn't about seeking happiness, but about feeling more intensely - higher highs, but also lower lows. "If you want to be happy all the time, awe is not for you," he writes. "It's too upsetting and causes too much uncertainty." Being that alive - that immersed in experience - is exposing; it involves not "closure" but "open-ture". (Excessive happiness actually works against the state of growth and engagement psychologists call "flourishing": the bizarrely precise conclusion of the researcher Barbara Fredrickson is that the healthiest ratio of happy to sad feelings is 2.9:1. Sure enough, Pearsall found those closest to that point reported the most awe.)

His book has a terrible twist. After Pearsall submitted the manuscript, he recounts in an epilogue, his son committed suicide, aged 35. Pearsall and his wife discovered the body. "I am now writing in one of the most intense, deep, painful aspects of awe... I know there won't be 'closure' or 'getting past' what's happened," he writes. "If I can stay in awe of what's happening, I won't expect answers. I don't want there to be [any]... I want to yearn, grieve, and cry for our son for the rest of my life."

And then, arrestingly, this phrase, which might seem baffling out of context: "I feel more alive than I've ever felt."

oliver.burkeman@theguardian.com