In a study published in the June 2011 issue of Science, University of Washington researchers studied how sleep might impact long-term memories. How? By using a special breed of fruit flies that could be induced to sleep on demand.
First, the male flies studied in this paper were trained by being exposed to other, genetically engineered males who released female pheromones. The flies tried to court these false females, with no results. After several failed attempts, half of these flies were then forced to sleep for 4 hours.
When later reintroduced to the the engineered males, these sleepers made no further courtship attempts suggesting that sleep had helped form a long-term memory of the earlier deception. Flies who didnt sleep, on the other hand, continued to fall for the same trick.
The researchers in this study concluded that training alone was not enough to trigger memory consolidation sleep was a necessary component. While this studys results dont necessarily carry over to humans, they help cast the role of sleep in a new light.