Lack of sleep affects many areas of an individual?s life. Researchers at Beth Israel Deaconess Medical Center (Boston, Mass) looked at the effects of chronic sleep restriction on cognitive function, with an emphasis on working memory. For the study, the researchers examined the working memory capacities of 12 participants over 9 days. Seven participants slept 4 hours a night and 5 participants slept 8 hours a night.
Every morning, the participants performed a computer task to measure how quickly they could access a list of numbers 1, 3, or 5 items long that they had been asked to memorize. Then they were given a series of single digits and were asked to answer ?yes? or ?no? to indicate whether each digit was among those they had memorized. The investigators measured the speed of their responses. The longer it took participants to respond, the less efficient was their working memory.
If fatigue were the reason why the individuals were slower at pushing the buttons to answer ?yes? or ?no,? their response times for the 1-, 3-, and 5-item tasks would have decreased equally over time. The results showed that participants who slept 8 hours a night gradually improved their working memory efficiency on this task. Yet, the participants who slept only 4 hours did not show any improvement in memory function.