Dean Burnett, 35, is a Cardiff-based neuroscientist, blogger and occasional standup comedian who writes the Guardian’s science blog Brain Flapping. His bestselling book The Idiot Brain, published in 2016, portrayed the human brain as an extraordinary organ that is also messy, fallible and disorganised. In his follow-up, The Happy Brain, Burnett delves into our grey matter once more to explore the slippery notion of happiness, asking: what causes it, and why? What makes our brain like certain things so much, but not others? Can eternal happiness actually exist – and would it be desirable anyway?

How did the book come about?
The publishers kept saying: “What’s your next book about then? We need another one.” I didn’t have any ideas, so I started asking friends and colleagues and got lots of suggestions, all very different and generally all rubbish. People kept saying: “At the end of the day you’ve just got to write about what makes you happy.” I’m a very literal person, so I took that at face value. What makes us happy? That branched out into why things make us happy, which turned out to be a very rich source of investigation – especially when there are so many self-help books and articles saying “The key to happiness is…”

You establish very quickly that it’s almost impossible to pinpoint an area of the brain that deals with happiness. Why is that?
There’s a common conception that the brain is modular, that it has different parts that do specific things. But that’s not how it works at all. It’s far more intertwined and complex. With raw sensory things such as vision and hearing, you can boil them down to basic inputs, such as the photons in your retina. Things like emotions and thought processes are far more intangible and abstract. So there’s no one place that does happiness.

Even trying to define happiness is tricky…
Exactly. The idea of happiness is so individual, so subjective. Nurture is a big factor in what ends up making us happy and how we experience pleasure in life.

You encounter some interesting people in your quest to better understand happiness. What prompted you to contact Charlotte Church, for example, and what did you learn from her?
I wanted to speak to someone about fame, and how it relates to happiness, and I thought Charlotte would be a good person to talk to, not just because she’s Welsh but also because she experienced so much fame so young. She told me that she hadn’t wanted to be famous, it didn’t really resonate with her. She’d say to her friends from school: “Yeah, I was doing the Grammys last week and Justin Timberlake sang a song for me.” Her friends would look at her blankly and say: “Yeah, well guess who got caught necking behind the bike sheds.” It wasn’t their world so she downplayed it. It goes to show that you can be as famous as possible but it doesn’t matter as much as the approval of the people you actually care about.

You make it clear at the outset that this is not a self-help book, but has researching it made you reassess the way you live, and make changes?
It’s definitely not a self-help book, but it has made me approach some things differently. I’m more conscious now of how much time I spend working and why it’s not always a good idea to work into the wee small hours. It’s important to stop sometimes, to say no to things, and let yourself recuperate – and to spend more time with the people you care about.

Your first book was an international bestseller. Did it make you happier?
I guess so, because I gave up my boring day job and now I’m a full-time writer. The sales were great, I can’t argue with that, but it was the ridiculous or incongruous things I enjoyed the most. Like when I was told that Whoopi Goldberg wanted to buy the TV rights to my book, and then I found myself doing a conference call with her on a rainy Monday evening in Cardiff. I got a kick out of that.

Is there a downside to happiness?
I think the current cultural perception of happiness as something you need to have, or else you’re some sort of failure, is unhelpful. Happiness shouldn’t be the default state in the human brain. If you’re constantly happy, why would you do anything? You need it as a motivator to make you do stuff, to get you through life. You need the full range of emotions and experiences to be able to appreciate things.

Including unhappiness?
Yes. I talked to a Welsh millionaire entrepreneur called Kevin Green and his point was that the most successful people he knows all went through a period of unhappiness. I also came across a piece in the Harvard Business Review that suggests the happiest employees aren’t necessarily the best employees: they are more demanding, they tend to expect more, and they have a lot more happiness to lose.

Do you think neuroscience will ever get to a point where it can make definitive statements about how happiness affects the brain and vice versa?
I think we could get to the point where we could definitively say: “This is what happens in the brain when someone does this.” But to say: “If you do this one thing then you’ll definitely be happy, regardless of who or where you are or what you’ve experienced” – that point is really far away, and I’m not sure how helpful that would even be. Do we really want to be automatons who can be controlled like that?

How do you think the media can improve the way it talks about the science of happiness?
If you are trying to give a better impression of how the brain works, I think an acknowledgment of its complexity and our lack of certainty would be useful. In my books and in blog posts, I go to pains to say “science suggest this” or “evidence implies”. The idea that there are definite answers to be had is unhelpful. So is the idea that it’s easy to be happy and that some people are. It suggests that if people aren’t happy it’s somehow their fault. Then you get into the whole “snap out of it” thing with regard to depression. We are moving away from that, but there’s still a ways to go.

What conclusions were you able to draw at the end?
The thing that kept coming across was just how important other people are to your happiness. Your interactions with them, their approval, their empathy, your shame, your ambitions to be famous – it all depends on other people and their presence in our lives. It’s harder to be happy in isolation than you might think; even if you are a proper hermit, you still know that people are out there and you could find someone if you wanted to. That was one of my overall conclusions, but if evidence comes up to prove it wrong, I would happily reject it.

• The Happy Brain by Dean Burnett is published by Guardian Faber (£12.99). To order a copy for £9.99 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99