From the Science website:
Asleep at the Memory Wheel
By Greg Miller
ScienceNOW Daily News
18 October 2006
ATLANTA, GEORGIA--Going a night without sleep may cause your hippocampus to go on strike. A new study has caught this crucial memory-encoding brain region slacking off in college students the day after they've pulled an all-nighter. The study is one of the first to investigate how sleep deprivation interferes with memory mechanisms in the human brain.
Neuroscientist Matthew Walker of Harvard University and his colleagues paid 10 undergraduate students to forgo a night's sleep. The next day, the students viewed a series of 30 words, and two days later--after having two nights to catch up on their sleep--the students returned to the lab and took a test to see how well they remembered the words they'd seen.
The students recalled about 40% fewer words overall than a group of 10 students who had slept normally, Walker reported here yesterday at the annual meeting of the Society for Neuroscience. But the researchers also found that the emotional content of the words made a big difference in what people remembered. Previous studies have found that both positive and negative emotions bolster memory, but in the current study, negatively charged words (such as cancer or jail) seemed to penetrate the sleep-deprived brain more deeply than positive ones (such as happy or sunshine). Indeed, sleep-deprived students were only 19% worse than their well-rested counterparts at remembering negative words, but 59% worse
for positive words. Walker suspects the difference may reflect an evolutionary safeguard against forgetting potential threats.
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