Visualizing an activity before you fall asleep can help ou remember to do it the next day.

RODALE NEWS, EMMAUS, PA—Do you need to remember to get your mom a birthday card? Or pick up a prescription at the drugstore? A new study suggests you should think about it before bed and then sleep on it. While previous research has already shown that sleep and memory are intricately linked, this new study, published online this month in Psychological Science, found that sleeping helps cement things we intend to do and helps us actually follow through on them the next day when we see a seemingly insignificant cue (such as a drugstore when we need that prescription).

THE DETAILS: The researchers wanted to study what's known as "prospective memory," which is basically the kind of memory that helps us remember things we intend to do but haven't done yet, as opposed to "retrospective memory," or things that have already happened. So they recruited 96 college students, who were divided into four groups. All the groups were asked to complete a series of three computer tests, during which the words "table" and "horse" would appear periodically. After all the tests had been explained, they were told to hit the letter "Q" each time they saw one of those words; this last little exercise served as the "intention."

One group was given the instructions in the morning and then asked to return at night to complete the actual test. Another group was given the instructions in the evening and asked to return the following morning for testing. A third group was given the instructions in the morning, sat through a 20-minute delay, and took the tests immediately, and a fourth group did the same thing in the evening. These last two groups served as the "controls" to overrule any assumptions that people who take tests in the morning do better than people who take tests in the evening.

The second group—those given instructions in the evening and asked to return the following morning for testing—performed the best on the "Q" test than any of the others. And, they scored best on the "Q" exercise during the third test, which had been explained immediately before they were told to hit "Q," than in the two others.