How Job Stress Can Age Us

I noticed my first gray hair during my medical residency. It sneaked up on me at the end of a long, frenzied shift — one of those nights when Murphy’s Law seems stronger than the law of gravity. Two of my patients did slip and fall, though, so Newton made a strong showing too.

The next day, I found another gray. Then another and another, until I stopped counting.

I was in my mid-20s, and it was the first time I’d noticed my body aging — not getting stronger or faster or wiser, but starting its decline. The human body performs so many impressive functions, I thought: It heals wounds, clears waste, digests Doritos. Can’t it find a little pigment to keep my hair colored?

This month, a new cohort of medical school graduates began their residencies. It’s no secret that medical training is an intense, sometimes grueling, process. But a new study, one of the first of its kind, shows how long hours, disrupted sleep and constant stress can take a biological toll on newly minted doctors. Down to the level of their genes.

Researchers at the University of Michigan tested the DNA of 250 first-year medical residents around the country. They took samples of their saliva to examine the length of their telomeres — the protective caps at the ends of chromosomes that prevent DNA damage — before and after the first year of residency.

Telomeres shorten every time our cells replicate, acting as a kind of fuse at the end of DNA. Once they become too short, cells know that it’s time to retire or self-destruct. Telomere attrition also plays a role in the aging process and is linked to many age-related diseases, including diabetes, cancer and heart disease.

Researchers found that the DNA of first-year residents aged six times faster than normal. Telomeres usually shrink at a rate of about 25 DNA base-pairs per year, but first-year medical residents experienced a decline of more than 140 base-pairs on average. Residents who worked longer shifts or more hours overall were at even higher risk: Telomere shrinkage increased steadily with the number of hours worked but skyrocketed for those working more than 75 hours per week to over 700 base-pairs.

“Most prior research on residency well-being has used self-reported questionnaires,” said Dr. Srijan Sen, the study’s senior author and an associate professor of psychiatry at the University of Michigan. “We hope that showing measurable physiological effects at the cellular level will help catalyze residency reforms that really move the needle.”

How long and how hard trainees should work is a subject of perennial debate in medicine. But it has new urgency amid growing recognition of widespread anxiety, depression, and burnout among medical trainees and physicians.

This study comes on the heels of other research showing that doctors in training lose three to seven hours of sleep per week and are much less physically active compared to their pre-residency lives. For some, a vicious cycle emerges: short sleep leads to worse mood the next day, which in turn makes it harder to sleep at night, culminating in a chronic depressive state.

The solution is not simply to reduce work hours — though avoiding extremely long workweeks would help. Becoming a doctor requires intense, repeated, constant immersion, such that diagnosis and treatment enter a kind of muscle memory. Most residents, some of whom are approaching 40 when they finish training, would probably balk at an offer to trade shorter hours for more years of training — even if it does cost them a little telomere.

But there are opportunities to improve well-being in medical training — many of which are commonplace in other industries. Consider something as basic as healthy food, which can be surprisingly scarce for doctors working evening or weekend shifts in the hospital. While the 20-somethings at Google and Facebook enjoy sparkling water and organic vegetables, most medical residents scrounge for greasy pizza, leftover Thai food, and sugary soda — something close to the opposite of what they recommend for their patients.

It also matters how residents work all those hours. Training programs should reduce the number of day-to-night transitions residents have to make, as these can lead to circadian rhythm disruptions and mood problems. All residencies incorporate lectures and educational conferences, but doctors in training are often too busy juggling pagers, paperwork or other demands to attend. Ensuring residents can actually participate in these educational activities would create a sense that learning is a real priority. And having more flexibility and autonomy over one’s work schedule is critical. Long hours are tough, but having to miss a close friend’s wedding is what really hurts.

Finally, structured wellness programs are emerging. Stanford’s Balance in Life program started in 2011 after the suicide of a surgical residency graduate, provides trainees with a comprehensive set of resources to support professional and personal well-being. A mentorship program allows junior residents to meet regularly with senior trainees and faculty members to discuss their concerns and goals. (Prior research has shown that the quality of resident-faculty interactions is linked to depression scores.)

Every six weeks, residents also meet with a clinical psychologist to share challenging experiences and discuss personal issues. While on call, they have access to a dedicated refrigerator stocked with healthful snacks and beverages. And all residents are encouraged to have regular checkups with their own doctor and dentist — ironically, an elusive luxury during medical training.

Medical training is — and needs to be — intense. Developing the skills and intuition needed to care for patients independently requires a certain exhaustive immersion. But too often our current system strains, instead of supports, trainees along their journey. That’s not good for doctors or for patients.

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