Newsletter #264

This week, I'd like to cover something that we haven't really tackled before. This topic was inspired somewhat serendipitously.

A few weeks ago, my poor old MacBook, which has served me faithfully for years, suddenly started having major issues, and I had to drop it off at a local electronic repair shop. To my immense relief, they were able to restore it to good working order.

However, it took longer than initially expected, because it was not easy for the technicians to source a replacement battery for this ancient laptop (they classified it as a "vintage" device, which should give you a sense for how old this thing is). That meant that the computer was out of commission for more than a week.

And since I don't have a backup computer, it effectively forced me to take a little break from my usual research and writing. While on my unplanned holiday, I started to wonder about vacations, and potential health effects associated with them.

This is actually a very relevant question, at least here in the US. According to the US Bureau of Labor Statistics, the average number of paid vacation days taken by Americans is just 11 days. This puts the United States almost at the very bottom globally in PTO. Worse still, it has been reported that more than half of Americans don't even use all of the vacation days that are allotted to them. Survey data showed that on average, Americans left 9.5 of their vacation days unused at the end of 2021.

Okay, so why might this matter from a health standpoint?

Well, one thing that has been robustly established, and which we have discussed previously in this newsletter, is that stress kills. Quite literally. And for most of us, one of the greatest sources of stress is work.

A good illustration of this can be found in a study that followed 812 initially healthy workers at a large Finnish company for more than 25 years who did not have cardiovascular disease at the start of the study. They found that job strain was associated with adverse changes in risk factors like cholesterol and BMI, and employees who were dealing with high job strain had a 2.2-fold higher risk of going on to die from heart disease.

There is reason to believe that taking breaks from work could ameliorate job strain — and it doesn't have to be very long or lavish to exert lasting benefits.

A study of Austrian middle managers found that a single short vacation (just four nights) had substantial positive effects on levels of stress and job strain. This impact lingered even 45 days after the end of the vacation, and was independent of the specific mode of the vacation.

That having been said, there is surprisingly little research out there that directly examines effects of vacations (or lack thereof) on long-term health outcomes. However, some retrospective analyses of prior cohorts — most of which were conducted before we recognized the connection between stress and the cardiovascular system — do shed light on this question, and are worth taking a look at.

Sometimes studies have perplexing results, and digging into the reasons behind these puzzling findings can inadvertently generate some useful information. The Helsinki Businessmen Study Intervention Trial was a multifactorial risk reduction intervention for clinically healthy men who had at least one cardiovascular risk factor at the start of the study. In the trial, 1222 men, deemed nearly identical at baseline, were randomly allocated into intervention and control groups. The lifestyle intervention did modestly improve risk factors (less smoking, healthier body weight, more physical activity, lower blood pressure, etc), and it cut their calculated cardiovascular risk nearly in half after five years. However, total mortality was consistently higher in the intervention group compared to the control group up to 25 years after the trial. What was going on here? Researchers wondered if there might be some other variable that they had overlooked which might explain this counterintuitive result. When they went back and analyzed baseline data, they noticed that shorter vacation time was an independent predictor of total mortality, and basically obliterated the long-term health benefits from the preventive intervention. Specifically, taking less than three weeks of vacation yearly was associated with 37% greater risk of early mortality in the intervention group.

The Multiple Risk Factor Intervention Trial (MRFIT) recruited a total of 12866 middle-aged men who did not have clinical evidence of coronary heart disease at the start of the study, based on physical examination or electrocardiography, but were deemed to be at high risk for the future due to measured risk factors. The men were randomly split into either a usual care group or an intervention group. During questionnaires that were administered during the first five annual visits, the men were asked whether they had taken a vacation over the past year. After adjusting for potential confounding variables, more frequent annual vacations were found to be associated with a 17% reduction in all-cause mortality, and a 29% reduced risk for cardiovascular mortality, during the 9-year post-trial period. Importantly, this relationship stayed significant after adjusting for education and income.

The Framingham Heart Study is a long-term ongoing cohort study of residents of a city in Massachusetts. It began in 1948, when very little was known about the causes of cardiovascular disease, and is now on its third generation of participants. Manifestation of heart disease in women was particularly ill-understood back then, since women were seldom recruited for observational research or intervention trials like the ones described above. To gain some insight, researchers repeatedly interviewed 749 female Framingham participants, who were free of heart disease at baseline. They asked them about various aspects of their lives, including stress and vacation habits, and also performed physical exams with blood work. They found that women who took a vacation once every six years or less had nearly eight times greater relative risk of having a heart attack or dying from heart disease, compared to women who took two vacations yearly. This association remained after controlling for other factors like obesity, smoking, and socioeconomic status.

🚀 A coal miner in Kentucky successfully scammed people by claiming he was Adolf Hitler and that he needed donors to support the development of atomic bombs and spaceships.

After WWII, there was an array of conspiracy theories surrounding the death of Adolf Hitler, generally claiming that his suicide had been faked and he had actually escaped Berlin.

This notion, in general, was a lot more widely accepted than you might think — a 1947 Gallup poll found that 45% of Americans believed that Hitler was still alive somewhere.

Taking full advantage of this situation, a man began releasing letters in 1946 claiming to be the Führer, attesting that he had escaped with Eva Braun to…Kentucky. Calling himself "Furrier No. 1," he said that he and thousands of dissidents were digging tunnels from Kentucky to Washington DC, and were planning a revolt to take over not just America, not even just the entire world, but the whole universe. Through this campaign, he was able to raise up to $15,000 (more than $165,000 in today's money).

Eventually, of course, it was determined that this man was not Adolf Hitler, but rather a 61-year-old coal miner named William Henry Johnson, who was subsequently convicted of mail fraud in 1956.

Why Zebras Don’t Get Ulcers. By Robert Sapolsky.

The physiological stress response is highly conserved across different animal species. Fish, birds, reptiles, mammals, etc all secrete certain hormones (adrenaline and glucocorticoids) in reaction to stressors in the environment.

Now, this response is adaptive in the face of danger. Like, say, if you are a zebra running from a lion on the savannah. But humans are somewhat unique because although most of us are never confronted with mortal peril like the zebra, we nevertheless manage to induce this physiological stress response in ourselves (and in each other). And over time, this destroys our bodies.

In this classic book, Dr. Sapolsky explains how prolonged exposure to psychosocial stress affects nearly every organ system – increasing atherosclerosis, suppressing the immune system, shutting down reproduction, disrupting digestion, deranging blood glucose metabolism, etc. Much of Sapolsky’s insights emanate from his decades of research on African baboons in Kenya. These animals are highly social primates that are generally safe and well-fed, but are subject to psychological stress due to interactions with one another. And it turns out that they pay the price for these elevated stress hormones – much like we do.

If you want to really understand the impact of psychosocial stress on health, this is a must-read. Very approachable and layperson-friendly.

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Stress and Cognition (from Daily Performance and Stress)

This week, we’d like to highlight one of the lessons from our Daily Performance and Stress course.

This lesson addresses the somewhat complicated relationship between stress and our brain performance. Why do we sometimes seem to perform better when we’re under pressure?

Indeed, some of us practically rely on stress to get stuff done, although this is probably not ideal, as you’ll see in the video.

And how do different “doses” of stress affect the structure and function of key parts of the brain? 🤔

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