When Thinking Makes Us Tired

My neighbor and I were talking recently about our partners, both of whom are teachers. We agreed that we admired them for doing such a challenging job.

“I couldn’t do it,” my neighbor said, shaking his head with a wry smile.

“Me neither.” I smiled too. “I mean, I physically couldn’t do it!”

He paused and cocked his head. “I mentally couldn’t do it…” he said, trailing off, unsure what I meant.

“I physically couldn’t do it,” I repeated.

I wasn’t quite sure how to explain myself, and the conversation moved on. My neighbor knew about my ulcerative colitis, and he probably thought I was saying I couldn’t handle the physical aspects of a teacher’s job, like standing in front of a class all day or walking from desk to desk checking on students’ work.

But what I meant was that the mental work of teaching would be too physically strenuous for me.

If you’re healthy, the term “physically strenuous” probably conjures images of manual labor, such as construction work or custodial jobs. But I’m a chronically ill person who struggles with fatigue, and for me, mental work, too, can be physically taxing, so that thinking hard for long periods often makes me need to lie down.

I’m willing to bet this form of fatigue is relevant to healthy people, too. If thinking makes me tired, it probably makes all of us tired—we just don’t always realize it.

Ever since my diagnosis with ulcerative colitis, and especially since my health crisis in 2016, my struggles with fatigue have made me acutely aware of the subtle energy drains we all face in our society. My body is like a canary in a coal mine. Since my “battery” is perpetually low, I’m always just a few notches above exhaustion, and this gives me a special perspective on which aspects of modern life tire us out.

There are so many energy drains nowadays. The household clutter of our many possessions. The buzzing energy of the digital world. The constant stress of the news. And perhaps most of all, the perpetual treadmill of logistics to manage: paying bills, repairing broken appliances and cars, tracking schedules, buying groceries, going to appointments.

These days, we all need a lot of thinking to get by, and especially the left-brained thinking that’s required for juggling the minutiae of our day-to-day lives. I’ve found that it’s this kind of thinking that drains me most of all. Left-brained thinking—about logistics or finances or the organization of details—makes my gut clench and my brow furrow, even though I’m good at it and sometimes even enjoy it. Over time, it wears on me more than other, more creative but less detailed kinds of thought.

I can’t prove that I’m right that certain kinds of thinking make us more tired than others. Scientific American says that although the brain burns a surprising number of calories, science hasn’t proven that thinking hard burns significantly more calories than regular thinking. I haven’t researched whether there are studies on different kinds of thinking and their impacts on the brain and body. So I’m just writing from my own experience.

But in my experience, a couple hours of detailed, complex, left-brained thought often leaves me physically exhausted.

In my old job, I worked at a local watershed council, and my main tasks involved applying for and reporting on grants and permit applications for stream restoration projects. All that reporting meant endless details and logistics to keep track of. I had eleven projects altogether, and I relied on a giant, color-coded Excel spreadsheet to manage them all. This kind of complex, multitasking job had always been my forte, and in the past, when I was healthy, I could handle the mental fatigue that came with it. When my brain felt fried, I would just switch tasks, which gave the tired parts of my mind a break.

(Still, even back in those healthy days, I would sometimes come home so zonked that I’d ask Ron to “scramble my brain”—my term for a move in which he took my head in both his hands and waggled it back and forth, which felt like it literally loosened my overwound mind and got the juices flowing again.)

But ever since my 2016 health crisis, it’s no longer so easy to recover from mental fatigue. Now, when one part of my brain gets tired, often my whole brain and body are too, so that I need to physically rest, taking a nap or lying on the couch and watching something slow and soothing.

This is what I meant in my comment to my neighbor. Like him, I couldn’t handle the mental work of teaching—teachers have to be “on” all day, which would be exhausting for anyone. But for me, that exhaustion would translate to my body. Ultimately, I’d have to lie down and rest—something teachers can never do.

If I’m correct that left-brained thinking is tiring for most people, it doesn’t bode well for our modern world. Humans didn’t evolve to be thinking all day. We’re designed for long interludes of brain rest, in which our ancestors would have done relatively mindless tasks like walking through forests, gathering berries, or building fires.

More and more, as the world complexifies and digitizes, we’re losing the inefficiencies that used to allow us to rest our minds. Just decades ago, writing a message still involved not only writing but also folding a piece of paper, stuffing it into an envelope, and walking it to the mailbox, whereas now, we mostly just fire it off in an email. That means all those old, in-between moments of brain rest are lost. They may have been inefficient, but they were valuable for our well-being.

This state of affairs especially doesn’t bode well for straight women, who get stuck with far too much of the mental burden of running households even when they have jobs as demanding as those of their male partners. I often wonder if that extra mental burden, and the stress and exhaustion it brings, partly explains the fact that women are far more likely to develop autoimmune diseases than are men. Are women becoming so mentally exhausted it’s making us physically sick?

And the pandemic has exacerbated the problem (for everyone) by adding a whole new, complex layer of logistics to think about. In our workplaces, schools, shopping, social gatherings, travel, and everything else we do, we’re now tracking new concerns about the vaccination status of our friends and family and colleagues, the quality and care and proper use of our masks and everyone else’s, and the many new rules and workplace changes that are constantly in flux.

It’s no wonder so many people are overwhelmed and on edge. The world was already exhausting before the pandemic—exhausting mentally, and therefore, exhausting physically too. Of course this extra layer of mental work feels like too much.

One solution, in our individual lives at least, is to recognize this brain-body connection. Rather than seeing mental and physical fatigue as separate, it’s better to listen to our bodies when they tell us they’re tired from thinking.

As a healthy person, it used to be tempting for me to power through physical exhaustion if I misinterpreted it as “only” mental fatigue. After a hard day at work, I might ask Ron to “scramble my brain,” but then I’d go for a run or do other vigorous physical exercise, reasoning that after all, I was only mentally tired, not physically tired. I wanted my body to stay in shape, and I thought of my brain and my body as separate. I figured my brain could rest while my body ran.

Now I see that that powering through wasn’t generally good for me. Pushing through exhaustion activates stress hormones like adrenaline and cortisol, making us more prone to illness and burnout.

I should have paid more heed when my actual limbs and muscles felt fatigued, instead of assuming they couldn’t “really” be fatigued because I hadn’t exercised them. It would have been better to rest both my brain and my body when I felt physically exhausted, perhaps just opting for a moderate walk and some slow stretching.

Whether you’re healthy or living with your own chronic illness, if you’re struggling with exhaustion, my advice is to be gentle with yourself and listen to your body. Moderate exercise, like a slow walk or gentle yoga, might be just the thing when your body says it’s tired. Or you can rest altogether: turn off the internet, take a bath, calm your nerves with abhyanga, or relax with a fiction book or a show that isn’t overly stimulating.

You’ve probably been doing extra mental work lately, and mental work can be physically strenuous. Go easy on yourself.