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MEDICINE
Lost Memories--A Side Effect of Education?
Chronic stress and lack of sleep go with the territory of being a medical trainee. Yet new research in the neurosciences shows that the habit of working too much and sleeping too little has brain-altering effects that may prevent medical students, interns, and residents from accomplishing their most important task--learning.
"The intern typically wakes up and begins a 36-hour vigil," said Charles Czeisler. He and other conference participants described how lack of sleep and other forms of stress can interfere with medical education. (Photo by Steve Gilbert)
The new research was the subject of an afternoon symposium, "How the Brain Learns: Implications for Medical Education from the Neurosciences and Cognitive Theory," held on Sept. 23 and sponsored by the Academy at HMS. The unique focus yielded some provocative insights as participants discussed the effects of the medical school lifestyle, in particular chronic stress and sleep deprivation, on aspects of the brain, such as its ability to make new neurons.
Princeton Univerity's Elizabeth Gould and colleagues described how stress--defined as stimuli that activate the hypothalamus-adrenal-pituitary axis--can impair new neuron-making. Charles Czeisler painted in discomfiting detail the grueling schedule of the average medical trainee and its often dangerous consequences. "Currently, interns and residents work up to 140 hours a week," said Czeisler, HMS professor of medicine at Brigham and Women's Hospital. They are often asked to perform demanding cognitive and motor tasks, often very shortly after waking. Yet studies show that the transition from sleep to wakefulness often requires the better part of an hour. "The brain does not go from 0 to 70 in 60 seconds," Czeisler said.
Sleep deprivation is extreme in interns and residents, but medical students practice their own version. "Harvard students participate in what I call sleep bulimia," said Robert Stickgold, HMS assistant professor of psychiatry. He and his colleagues have shown that not sleeping the night after learning a new task, or even sleeping less than the ideal eight hours, greatly impairs learning (see Focus Dec. 1, 2000). It does so, at least in part, by depriving the brain of REM, or dream, sleep, which appears to play a critical role in forming new memories.
Other experiments by Stickgold's group suggest that rather than literally replay the day's events, dreams arrange those events in new contexts, producing meaningful associations with previously held information (see Focus Oct. 27, 2000). Meaning is something our waking brains seek out too, said Daniel Schacter, Harvard University professor of psychology. In experiments, meaningful words were better remembered. Schacter and colleagues also found that such words often triggered special brain regions.
As important as meaning may be, emotions may be more important, said Daniel Tosteson, the Caroline Shields Walker distinguished professor of cell biology, during the discussion after the presentations. "It has long struck me," he said, "that the most important determinants of learning are not cognitive but affective."
--Misia Landau
Copyright 2002 by the President and Fellows of Harvard College
