When I was in college, I spent many late nights cramming for exams. Inevitably, as the hour became later and later, I would give in to fatigue and go to sleep, reasoning that I would be better off finishing my studying after a good night's rest. This, of course, did not always work out the way I'd planned, and new research supports what I'd experienced firsthand.

In fact, according to a new study, facts and information are most effectively retained in your memory when you think about it first, then sleep on what you've learned. Thus, sleep enhances our ability to remember things that we need to do at a future date, a process known as prospective memory (PM). Getting a good night's sleep allows people to accomplish what they set out to do more effectively than when they try to accomplish it before going to sleep.

Interestingly, scientists found that the key for a person to carry out their intentions is not so much the time and effort spent in locking it into their memories, but is instead more a function of specific triggers related to the context of a person's circumstances or surroundings, not unlike Proust's madeleine.

The original goal of the study, published in the journal Psychological Science, was to examine the relationship between memory and sleep, specifically comparing PM to things that have happened in the past, also known as retrospective memory (RM). A majority of the scientific literature regarding sleep and memory involves RM, making the current study the first to examine the effects of sleep and PM.

Researchers tested four different groups of student volunteers. Of the two control groups, one was tested in the morning and one was tested at night in order to account for any effect that biological clocks may have had. A third group was prepared for testing in the morning for an exam given that night, 12 hours later, before going to sleep. The fourth group was taught in the evening, allowed to go to sleep, and then tested the next morning. Embedded in the tests were cues to measure the PM of the subjects.

What the scientists found was that the students who tested in the morning following a good night's sleep performed better in the test where context played a role in remembering. In the group that tested before going to bed, no such relationships were seen.

In other words, those who were rested performed better in terms of prospective memory than in other categories, and sleep helped to strengthen weak associations that assisted people in remembering their intentions.

Researchers believe that during the early period of our sleep cycle, which is known as slow wave sleep, prospective memory processes are active. Slow wave sleep involves interaction between the hippocampus, which is important for memory formation, and the cortical regions of the brain. During slow wave sleep, the hippocampus takes information and places it in the long-term storage areas of the brain.

The take home message from all of this is that if you have important things you have to remember in the next day or two, including information for work or exams, don't wait until the last minute, but rather spend the time the night before to process the information, and then sleep on it.