By Steven Kotler, published on March 1, 2005 - last reviewed on October 4, 2011
We go to college to learn, to soak up a dazzling array of information intended to prepare us for adult life. But college is not simply a data dump; it is also the end of parental supervision. For many students, that translates into four years of late nights, pizza banquets and boozy weekends that start on Wednesday. And while we know that bad habits are detrimental to cognition in general—think drunk driving—new studies show that the undergrad urges to eat, drink and be merry have devastating effects on learning and memory. It turns out that the exact place we go to get an education may in fact be one of the worst possible environments in which to retain anything we've learned.
Normal human beings spend one-third of their lives asleep, but today's college students aren't normal. A survey of undergraduates and medical students at Stanford University found 80 percent of them qualified as sleep-deprived, and a poll taken by the National Sleep Foundation found that most young adults get only 6.8 hours a night.
All-night cramfests may seem to be the only option when the end of the semester looms, but in fact getting sleep—and a full dose of it—might be a better way to ace exams. Sleep is crucial to declarative memory, the hard, factual kind that helps us remember which year World War I began, or what room the French Lit class is in. It's also essential for procedural memory, the "know-how" memory we use when learning to drive a car or write a five-paragraph essay. "Practice makes perfect," says Harvard Medical School psychologist Matt Walker, "but having a night's rest after practicing might make you even better."
Walker taught 100 people to bang out a series of nonsense sequences on a keyboard—a standard procedural memory task. When asked to replay the sequence 12 hours later, they hadn't improved. But when one group of subjects was allowed to sleep overnight before being retested, their speed and accuracy improved by 20 to 30 percent. "It was bizarre," says Walker. "We were seeing people's skills improve just by sleeping."
For procedural memory, the deep slow-wave stages of sleep were the most important for improvement—particularly during the last two hours of the night. Declarative memory, by contrast, gets processed during the slow-wave stages that come in the first two hours of sleep. "This means that memory requires a full eight hours of sleep," says Walker. He also found that if someone goes without sleep for 24 hours after acquiring a new skill, a week later they will have lost it completely. So college students who pull all-nighters during exam week might do fine on their tests but may not remember any of the material by next semester.
Walker believes that the common practice of back-loading semesters with a blizzard of papers and exams needs a rethink. "Educators are just encouraging sleeplessness," says Walker. "This is just not an effective way to force information into the brain."
Walk into any college cafeteria and you'll find a smorgasbord of French fries, greasy pizza, burgers, potato chips and the like. On top of that, McDonald's, Burger King, Wendy's and other fast-food chains have been gobbling up campus real estate. With hectic schedules and skinny budgets, students find fast food an easy alternative. A Tufts University survey found that 50 percent of students eat too much fat, and 70 to 80 percent eat too much saturated fat.
But students who fuel their studies with fast food have something more serious than the "freshman 15" to worry about: They may literally be eating themselves stupid. Researchers have known since the late 1980s that bad eating habits contribute to the kind of cognitive decline found in diseases like Alzheimer's. Since then, they've been trying to find out exactly how a bad diet might be hard on the brain. Ann-Charlotte Granholm, director of the Center for Aging at the Medical University of South Carolina, has focused on trans fat, widely used in fast-food cooking because it extends the shelf life of foods. Trans fat is made by bubbling hydrogen through unsaturated fat, with copper or zinc added to speed the chemical reaction along. These metals are frequently found in the brains of people with Alzheimer's, which sparked Granholm's concern.
To investigate, she fed one group of rats a diet high in trans fat and compared them with another group fed a diet that was just as greasy but low in trans fat. Six weeks later, she tested the animals in a water maze, the rodent equivalent of a final exam in organic chemistry. "The trans-fat group made many more errors," says Granholm, especially when she used more difficult mazes.
When she examined the rats' brains, she found that trans-fat eaters had fewer proteins critical to healthy neurological function. She also saw inflammation in and around the hippocampus, the part of the brain responsible for learning and memory. "It was alarming," says Granholm. "These are the exact types of changes we normally see at the onset of Alzheimer's, but we saw them after six weeks," even though the rats were still young.
Her work corresponds to a broader inquiry conducted by Veerendra Kumar Madala Halagaapa and Mark Mattson of the National Institute on Aging. The researchers fed four groups of mice different diets—normal, high-fat, high-sugar and high-fat/high-sugar. Each diet had the same caloric value, so that one group of mice wouldn't end up heavier. Four months later, the mice on the high-fat diets performed significantly worse than the other groups on a water maze test.
The researchers then exposed the animals to a neurotoxin that targets the hippocampus, to assess whether a high-fat diet made the mice less able to cope with brain damage. Back in the maze, all the animals performed worse than before, but the mice who had eaten the high-fat diets were most seriously compromised. "Based on our work," says Mattson, "we'd predict that people who eat high-fat diets and high-fat/high-sugar diets are not only damaging their ability to learn and remember new information, but also putting themselves at much greater risk for all sorts of neurodegenerative disorders like Alzheimer's."
It's widely recognized that heavy drinking doesn't exactly boost your intellect. But most people figure that their booze-induced foolishness wears off once the hangover is gone. Instead, it turns out that even limited stints of overindulgence may have long-term effects.
Less than 20 years ago, researchers began to realize that the adult brain wasn't just a static lump of cells. They found that stem cells in the brain are constantly churning out new neurons, particularly in the hippocampus. Alcoholism researchers, in turn, began to wonder if chronic alcoholics' memory problems had something to do with nerve cell birth and growth.
In 2000, Kimberly Nixon and Fulton Crews at the University of North Carolina's Bowles Center for Alcohol Studies subjected lab rats to four days of heavy alcohol intoxication. They gave the rats a week to shake off their hangovers, then tested them on and off during the next month in a water maze. "We didn't find anything at first," says Nixon. But on the 19th day, the rats who had been on the binge performed much worse. In 19 days, the cells born during the binge had grown to maturity—and clearly, the neurons born during the boozy period didn't work properly once they reached maturity. "[The timing] was almost too perfect," says Nixon.
While normal rats generated about 2,500 new brain cells in three weeks, the drinking rats produced only 1,400. A month later, the sober rats had lost about half of those new cells through normal die-off. But all of the new cells died in the brains of the binge drinkers. "This was startling," says Nixon. "It was the first time anyone had found that alcohol not only inhibits the birth of new cells but also inhibits the ones that survive." In further study, they found that a week's abstinence produced a twofold burst of neurogenesis, and a month off the sauce brought cognitive function back to normal.
What does this have to do with a weekend keg party? A number of studies show that college students consume far more alcohol than anyone previously suspected. Forty-four percent of today's collegiates drink enough to be classified as binge drinkers, according to a nationwide survey of 10,000 students done at Harvard University. The amount of alcohol consumed by Nixon's binging rats far exceeded intake at a typical keg party—but other research shows that the effects of alcohol work on a sliding scale. Students who follow a weekend of heavy drinking with a week of heavy studying might not forget everything they learn. They just may struggle come test time.
If this ledger of campus menaces worries you, here's something you really won't like: Smoking cigarettes may actually have some cognitive benefits, thanks to the power of nicotine. The chemical improves mental focus, as scientists have known since the 1950s. Nicotine also aids concentration in people who have ADHD and may protect against Alzheimer's disease. Back in 2000, a nicotine-like drug under development by the pharmaceutical company Astra Arcus USA was shown to restore the ability to learn and remember in rats with brain lesions similar to those found in Alzheimer's patients. Granholm, the scientist investigating trans fats and memory, found that nicotine enhances spatial memory in healthy rats. Other researchers have found that nicotine also boosts both emotional memory (the kind that helps us not put our hands back in the fire after we've been burned) and auditory memory.
There's a catch: Other studies show that nicotine encourages state-dependent learning. The idea is that if, for example, you study in blue sweats, it helps to take the exam in blue sweats. In other words, what you learn while smoking is best recalled while smoking. Since lighting up in an exam room might cause problems, cigarettes probably aren't the key to getting on the dean's list.
Nonetheless, while the number of cigarette smokers continues to drop nationwide, college students are still lighting up: As many as 30 percent smoke during their years of higher education. The smoking rate for young adults between the ages of 18 and 24 has actually risen in the past decade. All this news makes you wonder how anyone's ever managed to get an education. Or what would happen to GPAs at a vegetarian university with a 10 p.m. curfew. But you might not need to go to such extremes. While Granholm agrees that the excesses of college can be "a perfect example of what you shouldn't do to yourself if you are trying to learn," she doesn't recommend abstinence. "Moderation," she counsels, "just like in everything else. Moderation is the key to collegiate success."