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(CNN) Dr. Stuart Brown is an expert in having fun.

For more than 60 years, the 89-year-old psychiatrist and clinical researcher has studied the importance of play — in young and adult humans, as well as animals of all kinds.

Play is important for all of us on an instinctual level, his findings have suggested. In short, he believes we're our best selves when we're having fun.

Following years of private practice as a physician, Brown first dived into these studies as a psychiatrist at Baylor University in Waco, Texas. From there, he went on to start the nonprofit National Institute for Play, and he produced a three-part PBS series titled "The Promise of Play." He also coauthored the 2010 book "Play: How it Shapes the Brain, Opens the Imagination, and Invigorates the Soul."

In conjunction with Chief Medical Correspondent Dr. Sanjay Gupta's "Chasing Life" podcast, CNN talked with Brown to discuss his work, and to learn more about how embracing play can lead to greater enjoyment and less stress.

This conversation has been edited and condensed for clarity.

CNN: Why do we need play?

Stuart Brown: Like sleep and dreams or the immune system or the digestive system, play is part of the need of an animal for its developmental solidarity and social belonging. If you have play deprivation, you have long-term outcomes that are deleterious.

Play therefore is not trivial, not frivolous. It is important for physical and social health. I have studied 6,000 individuals and did a detailed review of their play backgrounds (and have seen) the importance and necessity of play itself and the consequences of play deprivation. One begins to see that play itself in giraffes, dogs, birds, bonobos and humans is a phenomenon of nature. It seems that the more learning an animal is capable of, the more important play is to the development of the species.

CNN: You mentioned play as being equally important to other animals. Is that really a thing?

Brown: It is! Rats, for instance, are very playful when they are developing. From weeks four to 15, all they do is wrestle and rough-and-tumble play with each other. If you surgically remove the cerebral cortex of a rat at birth, you would think that the subsequent play behavior would be totally messed up. But, lo and behold, these rats play almost indistinguishably from normal rats. This means that the wiring of rats' brains is subcortical. It's deep. It's fixed. When you consider that rats have the same neurotransmitters in their brain stem as we humans do, this suggests that all highly playful mammals have the capacity to play as a fundamental part of their instinct.

CNN: In the United States, adults tend to separate work and play. Is this a good idea?

Brown: In an ideal world, work and play should be indistinguishable. If you're a garbage collector in Brazil, that's a tough job and you're not paid much. But if you're drumming and dancing between pickups, you're enjoying the work and you're experiencing play. The choice of a vocation is important, and one hopes it would fit what engages that person, so work doesn't necessarily always feel like work. The evidence we get from animal play and brain size is that when play is fostered, competent learning and emotional stability and many other good things result.

If it is at all possible, we should be living lives where play is incorporated into everything we're doing. When I was a kid and we did evening dishes, we would sing rounds. That allowed a combination of pleasure and work to go together. I helped produce a series for the BBC called "Soul of the Universe." In it, I got to interview different Nobel laureates, and most of them didn't separate work and play. When they talked about what they were doing in their labs, they were like kids in the playground.

CNN: How does play differ for kids?

Brown: Kids need play from the very beginning. Parents should even consider it as they contemplate parenthood, and they should look at their own play lives to have some exploration into the joy their offspring needs to be nourished. Instead of saying, "I want my son to be a lawyer or a doctor," they should look at a child and say, "What is it that produces natural gleefulness for this child?" Maybe it's being tickled. Maybe it's listening to music. Maybe it's being tossed up in the air, or social contact with baby talk.

A crucial part of parenting is understanding and reinforcing the natural play proclivities of your child from infancy, Brown said.

Very early on, you begin to get a sense of your child's natural play personality. From there, parents should let the child seek out and do a lot of the reinforcement based on their own natural play proclivities. I understand parenting is complex and made up of all kinds of things that happen. But play is a strong universal drive in all children. Noticing and reinforcing the natural play qualities of infants and seeing how their natural talents are often allied with their playfulness is an important part of parenting.

CNN: To what extent can kids learn through play?

Brown: Curiosity and play is in part guaranteed to add to the learning and competency of developing kids. This is why kids climb up slides and risk failing as they try the monkey bars — because learning to assess risk is definitely something kids do through play. The more they play, the more kids learn from others what constitutes capacity within their own bodies and how they socialize within the context of that. Good play is a learned language that requires time and exposure.

CNN: With the climate crisis impacting our ability to interact with the environment and the economy worsening for many, how do we make sure we incorporate play?

Brown: Despite everything going on around us, play allows us to explore what's possible. Innovation, creative problem solving — these are both related to the fulfillment of our playful nature. One of the reasons I think play is still a big part of human nature is that it helps us deal with a changing world. If you are rigid and fixed, you are not going to have room to try to check possibilities that might not otherwise exist for you.

Play is important in solving some of these tough problems we have. Empathy is learned in part through rough-and-tumble play in preschool. If you don't have tolerance for people who are different than you, it's easier to go to war.

CNN: How can each of us incorporate more playfulness into our everyday lives?

Brown: It's important for all of us to prioritize the things that give us joy. Whether it's a memory of a vacation or a relationship, I think we all have the capacity to reach into our psyche and body and find playfulness, and that is an important part of being human. Even if there are financial and emotional traumas, there still is room for a joke or playfulness or for humor.

Play can come in many different forms. I have a neighbor who has a friendly dog named Cookie. Just this morning, I went for a walk, and Cookie and I shared a little eye contact. She gave me a lick of the hand, I gave her a pat on the head. Afterward, I felt great. These were moments of playfulness. It can be part of every day. We need to look at play as if it's as important as brushing our teeth and getting a good night's sleep or having good nutrition. We need it all to thrive.

Matt Villano is a writer and editor based in California. His work has appeared in The New York Times, CNN and elsewhere.
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