Now, American scientists have confirmed that lack of sleep affects a person's memory as it changes the function of the hippocampus ? a region in the brain vital for memory. Researchers from the Harvard University Medical School said sleep is crucial before a certain experience because getting enough of it can lead to the normal functioning of the memory system.

During the study to appear in the March issue of the journal Nature Neuroscience, one group was deprived of sleep for one night while the other group had a full night's sleep. They were then asked to observe and recall a set of picture slides for a recognition test. The scientists found that the hippocampus of those who didn't get some sleep was not functioning well compared to the control subjects. Those who were deprived of sleep also showed low recall abilities.

A previous study showed that sleeping for five hours after learning a certain task is vital for the memory. University of Pennsylvania researchers have found that mice allowed to take a nap after training recalled what they had learned than their counterparts that were sleep-deprived. They confirmed that sleep deprivation of up to five hours after learning affected contextual memory such as spatial orientation and recognition of surroundings. This is an additional proof that sleep does help in the normal functioning of the hippocampus.

Another study done by the Princeton University in New Jersey found that not getting enough sleep may lead the brain to cease producing new brain cells. The study on rats showed that lack of sleep for a long period of time affects the hippocampus of the brain. Rats that were deprived of sleep for three days had higher levels of corticosterone or the stress hormone and fewer new brain cells were produced in their hippocampus. After a week when their sleeping patterns were back to normal, their brain's ability to produce nerve cells was greatly affected for two weeks.

In pre-school children, new research has also shown that lesser than normal sleeping time affects their behavior during the day. A study by the Northwestern University scientists has found that children aged two to three who sleep less than ten hours each day have a tendency to show behavior problems like being disobedient, pretentious and aggressive. The researchers said that preschoolers who had less sleep at night are 25 percent likely to experience psychiatric diagnosis. These behavioral problems may also be attributed to a number of factors, according to the scientists. It's either lack of sleep leads kids to have behavioral problems or their daytime behavior leads them to sleep less than usual or a third variable like the child's tantrum or a parent's ability to structure sleep patterns and daytime behavior.

And so an important lesson learned here is to not take sleep for granted. Getting enough sleep gives us more energy and refreshes our memory for the next day's activities. Until then, sleep tight!