One day, it's a windfall; the next day, it's barely enough to cover your bills. That's the reality for gig workers, waiters, salespeople, and others who rely on fluctuating income, and – according to recent research published by the American Psychological Association – it's taking a toll on their health.

Dr Gordon Sayre, an assistant professor of organisational behaviour at Emlyon Business School in France, conducted three studies across various industries in the US, and the results were eye-opening. Workers who experienced more volatile pay reported worse physical health symptoms, ranging from poor sleep quality to headaches, stomach issues, and back pain. And it wasn't just limited to lower-paid tipped jobs or gig economy freelancers, but even higher-paid professionals in finance, sales, and marketing, where commissions and performance bonuses are common.

In one study, Dr. Sayre surveyed 85 workers in the US who relied on tips for their income, including waiters, delivery drivers, maids, and more. They reported receiving tips on 80% of their workdays, with an average daily tip total of $36.18, accounting for a quarter of their total income on average. However, large fluctuations in daily pay over two weeks were associated with negative physical health symptoms and poor sleep quality, especially when volatile pay comprised a larger percentage of their total income.

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The story was similar for gig workers on Amazon's Mechanical Turk, a website where workers complete various tasks for minimal pay. Dr Sayre surveyed 375 participants who spent an average of 29 hours per week on the platform, and the findings were clear – volatile pay was linked to worse health outcomes.

Even higher-income professionals weren't immune to the impact of volatile pay. Dr. Sayre conducted a final online survey with 252 finance, marketing, and sales employees who relied on commissions or bonuses for a smaller fraction of their income. Pay volatility was less harmful to their health when they were less reliant on those volatile forms of income. Still, mindfulness, or focusing on the present moment, didn't help reduce the physical symptoms of volatile pay.

So, what can be done to protect workers' health? Dr. Sayre suggests that businesses should consider whether volatile forms of pay, such as tips, piece-rate work, performance bonuses, and commissions, are necessary and ensure that more stable forms of compensation make up a larger proportion of workers' total income. He also advocates for legislative changes, such as raising the federal tipped minimum wage, currently set at a paltry $2.13 per hour, and providing greater protections to gig workers.

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"Unions are another way workers could secure stronger protections against volatile pay," Dr. Sayre added. "Raising the proportion of base pay and reducing dependence on volatile pay should help protect workers' health in many industries."

While the study findings do not prove that volatile pay causes health symptoms, the correlation is hard to ignore. As the gig economy continues to grow and more workers rely on unpredictable incomes, it's clear that something needs to change to ensure that workers' health doesn't pay the price for wage volatility. After all, a healthy workforce is a happy workforce, which we can all agree on.