Lack of sleep takes a toll on the brain
In the August 2004 issue of the journal Sleep, Dr. Timothy Roehrs, the Director of Research at the Sleep Disorders and Research Center at Henry Ford Hospital in Detroit, published one of the first studies to measure the effect of sleepiness on decision-making and risk-taking. He found that indeed it does take a toll on effective decision-making.
Cited in the October 12, New York Times Science section, Dr. Roehrs and his colleagues monetarily rewarded sleepy and fully alert subjects who completed a series of decisions and tasks. At random times, the subjects were given a choice to take their money and stop. Or they could forge ahead with the potential of either earning more money or losing it all if their work was not completed within the time remaining. A kind of “Who wants to be a Millionaire” science experiment.
Dr. Roehrs found that the alert people were very sensitive to the amount of work and time they needed to do in order to finish the tasks and understood the risk of losing their money if they didn’t. But the sleepy subjects chose to quit the tasks prematurely or they risked losing everything by trying to finish the task for more money, even though it was likely that they would not be able to finish.
According to the National Commission on Sleep Disorders Research (1998) and reports from the National Highway Safety Administration (NHSA, 2002), a high number of accidents can partly be attributed to people suffering from a severe lack of sleep.
Each year, according to the NCSDR, the cost of sleep disorders, sleep deprivation and sleepiness is estimated to be $15.9 million in direct costs and $50 to $100 billion a year in indirect and related costs. And according to the NHSA, falling asleep while driving is responsible for at least 100,000 crashes, 71,000 injuries and 1,550 deaths each year in the United States. Young people, in their teens and twenties, who are particularly susceptible to the effects of chronic sleep loss, are involved in more than half of the fall-asleep crashes on the nation’s highways each year. Sleep loss also interferes with the learning of young people in our nation’s schools, with 60 percent of grade school and high school children reporting that they are tired during the daytime and 15 percent of them admitting to falling asleep in class.
We’ve always known that sleep is good for your brain, but new research from the University of Rochester provides the first direct evidence for why your brain cells need you to sleep, and sleep the right way. The study found that when you sleep your brain removes toxic proteins from its neurons that are by-products of neural activity when you’re awake. Unfortunately, your brain can remove them only while you’re asleep. So when you don’t get enough sleep, the toxic proteins remain in your brain cells, wreaking havoc by impairing your ability to think — something no amount of caffeine can fix.
Skipping sleep impairs your brain function across the board. It slows your ability to process information and problem-solve, kills your creativity, and raises your stress levels and emotional reactivity. Basically, it affects your decision-making ability.
The mental work of making decisions time after time can wear you down. Decision fatigue is the newest discovery involving a phenomenon called ego depletion, a term coined by the social psychologist Roy F. Baumeister. This sort of fatigue can make quarterbacks prone to dubious choices late in the game, a CEO leans toward disastrous dalliances late in the evening or a recovering addict deciding to use after a long day at work. It routinely warps the judgment of everyone, executive, delivery driver, rich or poor — in fact, it can take a special toll on the poor. Yet few people are even aware of it, and researchers are only beginning to understand why it happens and how to counteract it.
Decision fatigue helps explain why ordinarily sensible people get angry at colleagues, splurge on clothes, pick up candy at the market’s check out lane and can’t resist the dealer’s offer to rustproof their new car. No matter how rational and high-minded you try to be, you can’t make decision after decision without paying a price. It’s different from ordinary physical fatigue — you’re not consciously aware of being tired — but you’re low on mental energy. The more choices you make throughout the day, the harder each one becomes for your brain, and eventually it looks for shortcuts, usually in either of two very different ways.
One shortcut is to become reckless: to act impulsively instead of expending the energy to first think through the consequences. (Sure, tweet that photo! What could go wrong?) The other shortcut is the ultimate energy saver: do nothing. Instead of agonizing over decisions, avoid any choice. Ducking a decision often creates bigger problems in the long run, but for the moment, it eases the mental strain. You start to resist any change, any potentially risky move — like releasing a prisoner who might commit a crime. So a fatigued judge on a parole board takes the easy way out, and the prisoner stays in prison.
These experiments on Decision Fatigue demonstrated that there is a finite store of mental energy for exerting self-control. When people fended off the temptation to scarf down M&Ms or freshly baked chocolate-chip cookies all day at the office, they were then less able to resist other temptations, like stopping for a bottle of brandy on the drive home. When they forced themselves to remain stoic during a tearjerker movie, afterward, they gave up more quickly on tasks requiring self-discipline such as brushing their teeth, taking off their make-up or sleeping with the guy that paid for the movie. Willpower turned out to be more than a folk concept or a metaphor. It really was a form of mental energy that could be exhausted.
In the rest of the animal kingdom, there aren’t a lot of protracted negotiations between predators and prey. A lioness doesn’t arbitrate with an antelope. To compromise is a complex human ability and therefore, it is one of the first abilities to decline when Decision Fatigue sets in. If you’re shopping, you’re liable to look at only one dimension, like price: just give me the cheapest. Or purchase only the products you have coupons for. Or purchase only the items which are covered by food stamps. Or limit yourself to only the $100. you have in your budget for groceries. And now, you have to put away the barrettes you got for your daughter, and the athletic socks for your son. Shopping can be especially tiring for the poor, who have to struggle continually with trade-offs.
Researchers argue that this sort of Decision Fatigue is a major, and a largely ignored factor in trapping people in poverty. Because their financial situation forces them to make so many trade-offs, they have less willpower to devote to school, work and other activities that might move them up into the middle class. It’s hard to know exactly how important this factor is, but there’s no doubt that willpower is a special problem for poor people.
Decision Fatigue is a reason that the liquor, candy and soda is displayed in the front of the store, featured prominently near the cash register, just when shoppers have depleted all their decisions in the aisles. With their willpower reduced, they’re more likely to yield to any kind of temptation, but they’re especially vulnerable to booze, candy and soda. While supermarkets figured this out a long time ago, only recently did researchers discover why.
Despite this series of findings, brain researchers did find that glucose is a vital part of willpower. They helped solve the puzzle of how it increases the brain’s energy. Your brain does not stop working when glucose is low. It stops doing some things and starts doing others. It responds more strongly to immediate rewards and pays less attention to long-term prospects. A perfect environment for alcohol abuse.
The discoveries about glucose help explain why dieting is a uniquely difficult test of self-control and why even those people with phenomenally strong willpower in the rest of their lives can have such a hard time losing weight. They start their day with virtuous intentions, resisting croissants at breakfast and dessert at lunch, but each act of resistance further lowers their willpower. As their willpower weakens late in the day, they need to replenish it. But to resupply that energy, they need to give the body glucose. They’re trapped in a nutritional catch-22:
1. In order not to eat, a dieter needs willpower.
2. In order to have willpower, a dieter needs to eat.
Fatigue at work
At work when we are fatigued, we are pretty good at avoiding the urge to spend money, but not so good at resisting the lure of relaxation, such as scrolling through Facebook, online shopping or viewing pornography on the web. Today there are so many choices to make. Your body may have dutifully reported to work on time, but your mind can escape at any instant. A typical computer user looks at more than three dozen Web sites a day and gets fatigued by the continual decision-making — whether to keep working on a project, or check out YouTube, or follow a link to another interesting research topic or buy something on Amazon. Ever wonder why Cyber Monday is one of the biggest shopping days of the year?
The cumulative effect of these temptations and decisions isn’t intuitively obvious. Virtually no one has a gut-level sense of just how tiring it is to decide. Big decisions, small decisions, they all add up. Choosing what to have for breakfast, where to go on vacation, what to do next, how much to spend from this paycheck— these all deplete willpower, and there’s no blinking indicator light on your dashboard to warn you that your willpower is low.
When the brain’s regulatory powers weaken, frustrations seem more irritating than usual. Impulses to eat, drink, spend and say stupid things have no filter and alcohol causes self-control to decline further. The Decision Fatigue effect was even demonstrated with dogs in two studies by Holly Miller and Nathan DeWall at the University of Kentucky. After obeying sit and stay commands for 10 minutes, the dogs performed worse on self-control tests and were also more likely to challenge another dog’s turf. Fatigued humans are also more likely to get into needless fights over turf. In making decisions, they take illogical shortcuts and tend to favor short-term gains (like ending the meeting and going home) and delay reviewing costs (yes even adding numbers up on a calculator is a decision).
“Good decision making is not a trait of the person, in the sense that it’s always there,” Baumeister says. “It’s a state that fluctuates.” His studies show that people with the best self-control are the ones who don’t schedule endless back-to-back meetings, they avoid temptations like all-you-can-eat buffets, and they establish good sleeping habits. Instead of deciding every morning whether or not to exercise, they work out with a friend. Instead of counting on willpower to remain robust all day, they conserve it so that it’s available for important decisions.
“Even the wisest people won’t make good choices when they’re not rested and their glucose is low,” Baumeister points out. That’s why the truly wise choose not to restructure the company at 4 p.m. Board meetings are not held at night. Major commitments are not made over cocktails. And if a decision must be made late in the day, they make sure they have eaten something like an apple or an orange to recharge their glucose levels. “The best decision makers,” Baumeister says, “are the ones who know when not to trust themselves.”
Next week’s post will feature tips and tools on how to achieve a good night’s sleep.
Resources for this article came from:
Baumeister, R.F., & Heatherton, T.F. (1996). Self-regulation failure: An overview. Psychological Inquiry, 7, 1-15.
Kathleen D. Vohs and Roy F. Baumeister, Running Head: Self-Regulation and Choice-Decision Fatigue Exhausts Self-Regulatory Resources-But So Does Accommodating to Unchosen Alternatives http://www.chicagobooth.edu/research/workshops/marketing/archive/ WorkshopPapers/vohs.pdf
Baumeister, R. F.; Sparks, E. A.; Stillman, T. F.; Vohs, K. D. (2008). “Free will in consumer behavior: Self-control, ego depletion, and choice”. Journal of Consumer Psychology 18: 4–13. doi:10.1016/j.jcps.2007.10.002.
Dr. Timothy Roehrs, (August 2004), The Journal Sleep, http://www.journalsleep.org/PDF/AbstractBook2004.pdf
Drowsy Driving and Automobile Crashes, NCSDR/NHTSA expert panel on driver fatigue and sleepiness,
Dr. Travis Bradberry (December, 2014), Sleep Deprivation Is Killing You and Your Career , Forbes Magazine,
John Tierney, (2011) Do you suffer from Decision Fatigue? New York Times Magazine,
Holly Miller (2014) Self-control without a “self?”: common self-control processes in humans and dogs Department of Psychology, University of Kentucky, Lexington, KY 40506-0044, USA.