Counting every minute? You may want to rethink that.

A new Stanford study graphically illustrates what productivity mania is doing to your body.

Life is short and busy. If you want to make both a good living and time to enjoy life’s pleasures, time management seems like an obvious solution. Keeping track of how you spend your minutes and thinking more scientifically about how you use them seems like a great way to accomplish important work and also have time to kick back and relax.

But while most people turn to time management as a way to reduce their stress levels, a growing list of experts is pushing back and arguing instead that hyper awareness of time actually increases our anxiety. Counting every minute just causes you to feel more frantic, folks like business psychologist Tony Crabbe have insisted.

Now a new study out of Stanford backs up their intuitions with hard science and biological data. Thinking of time as money, it turns out, doesn’t make you thrifty and efficient. It makes you physically stressed in a way that could damage your health.

Clock watching is bad for your health.

The study design was dead simple. The researchers recruited 104 volunteers to do paid work for a fictional company for two hours. The study subjects were split into two groups with one seemingly minor difference among them. While all the participants were paid the same amount for the same work, one group was explicitly told how much they were being paid per minute, offering them a concrete number to drive home Ben Franklin’s famous dictum that “time is money.”

You’d think just seeing your same old salary calculated differently wouldn’t have much of an impact on your stress levels, but when the researchers tested the subjects’ saliva for cortisol — a biological marker of stress that, when elevated over time, is associated with a bunch of pretty terrible health outcomes — those who were nudged to consider the economic value of every second saw a whopping 25 percent spike in their stress levels.

“A rise of almost 25 percent is a serious health consequence,” study co-author and Stanford Business School professor Jeffrey Pfeffer commented, but the damage your clock watching it doing to your body is only one unintended consequence of too much time management. It can also rob you of happiness, he warns.

“People are continually calculating the economic value of their time. And all the research shows that when people are thinking about time and money, they’re not enjoying their lives. They become impatient. They don’t enjoy music, or sunsets. This calculation of what it costs to coach your kid’s soccer game is not a path to happiness,” Pfeffer notes.

Time isn’t just money. It’s also your life.

What’s the lesson here? If you can afford to slouch through your days taking hours-long lunches and plenty of leisurely naps, both history and science actually suggest you’d probably get more meaningful work done if you did. And this study adds another benefit — your health will also probably improve. But, sadly, that’s not enough to convince many bosses and customers that such perceived “slacking” is acceptable.

So in the all-too-likely scenario where that’s not a viable option, the best approach is probably moderation. Thoughtfully organizing your days can almost certainly offer benefits, but don’t go too far. Allowing yourself plenty of short breaks (preferably away from both your phone and your desk) and the freedom not to account for every second will make you a lot happier and more productive than an obsessive focus on the economic value of every passing second.

This article was originally published at Inc.com.