Stay on your grind. Hustle harder. Sleep is for the rich.

You've heard those phrases promoting the idea that success, achievement and happiness are all enabled by a hefty bank account. That couldn't be further from the truth, says Laurie Santos, the psychology professor behind Yale University's most popular course and host of the podcast "The Happiness Lab."

"So many of us think, 'I'm going to put my head down and avoid social connection, whether it's at work or in my life, and I'm just going to hustle and get stuff done,'" Santos tells CNBC Make It. "That's just totally wrong."

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Working too hard can increase stress, depression and burnout, a Mayo Clinic blog post notes. It can even have "deleterious effects" on your occupational health — in other words, it's bad for both your health and your job performance — according to a 2019 meta-analysis published in the International Journal of Environmental Research and Public Health.

"We have an intuition [that] I'm going to earn a million dollars, and I'll be happy. Then you hustle, you get there and you're not happy," says Santos. "You think, 'I've got to hustle more ... Now I need $5 million to [be happy].' That hustle culture misconception winds up doubling down on itself."

You need sleep, rest and connection

Hustle culture has been around for a while. Workaholism has existed for even longer: The term was coined in 1971 by psychologist Wayne E. Oates, meant to characterize how work can become an addiction.

More recently, social media influencers pointed to Silicon Valley tech entrepreneurs as role models: If you optimize every moment of your day for maximum productivity, you can become rich just like them. Some took it a step further — if you don't sacrifice sleep and relationships for the sake of work, you won't ever be successful.

Yet people who get more quality sleep have greater life satisfaction than those who don't, found a 2018 study published in Frontiers in Psychology. The same is true for people who have strong social connections with others, Stanford Medicine reported in 2019.

"You need sleep, you need rest and you need connection with other people" to be happy, Santos says. "Those are the things that are going to matter."

Taking breaks in the workplace and reaching out more often to your family and friends can also go a long way, says Santos. Research backs her up here, too: "Social fitness" is the No. 1 key to a happy life, Marc Schulz and Robert Waldinger, directors of the Harvard Study of Adult Development, wrote for Make It in February.

"Social fitness requires taking stock of our relationships, and being honest with ourselves about where we're devoting our time and whether we are tending to the connections that help us thrive," Schulz and Waldinger wrote.

Hustle culture may already be shifting, according to a recent GoDaddy survey of 1,000 U.S. small-business owners. Fifty-four percent of respondents defined the American Dream as "feeling happy in life," marking a slide away from the more traditional response of wealth.

"The American Dream is changing, according to small-business owners," Fara Howard, GoDaddy's chief marketing officer, told Make It in July. "Economic conditions have resulted in homeownership being less attainable, particularly for members of Gen Z, while the pandemic and the Great Resignation have driven many to prize being their own boss and gaining more freedom, comfort and flexibility."

Correction: This story has been updated to reflect that a referenced study on quality of sleep and life satisfaction was published in Frontiers in Psychology.

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