Have a Good Night's Sleep to Help You Remember

Sleep memory
A good night's sleep not only preserves memories but helps with recalling previously forgotten information. Picture taken July 12, 2015. Vincent West/Reuters

A good night's sleep is a recipe for exam success and could also limit some of the debilitating effects of diseases like dementia on the memory, according to a new study.

The study, published in the scientific journal Cortex, found that a period of sleep could double the chances of someone remembering previously unrecalled information, when compared to a similar period of being awake.

It analysed two previous research papers involving participants who were asked to recall made-up words immediately after exposure, and then re-tested 12 hours later following either a night's sleep or a period of daytime wakefulness. The key distinction was between subjects who recalled the words both immediately and at the 12-hour retest, and those who did not remember immediately but recalled it at the retest. Sleep not only appeared to help people preserve information they already remembered, but also helped them to access memories which they could not recall when awake.

Nicolas Dumay, a psychologist at the University of Exeter and the author of the study, says that the findings have a number of implications beyond helping desperate students trying to cram the night before an exam. He says that the research proves that sleep helps not only with preserving information already remembered, but also with accessing weak memories which cannot be recalled while awake. "The inaccessible becomes accessible through sleep. This should be useful for those conducting crime witness interviews," he says.

Dumay says that a healthy amount of sleep can also help sufferers of degenerative memory disorders, such as Alzheimer's disease, to cope with some of the frustrating symptoms of memory loss. However, he says that sleep can by no means prevent the onset or repair the damage caused by such diseases. "Good quality sleep through all cycles in theory should alleviate for a while the deterring effect of dementia. However, there will be a point where the brain structure will have died out so much that the sleep regime will not be able to compensate," says Dumay.

Alzheimer's disease is the most common form of dementia. As of 2013, an estimated 44.4 million people worldwide suffered from dementia, with the number projected to more than triple to 135.5 million by 2050, according to Alzheimer's Disease International.

Dumay found that, during a stage of sleep known as slow wave sleep (sometimes called "deep sleep"), the brain switches from an "encoding mode" to a "consolidating mode" in other words, the brain stops taking in new information and focuses on maintaining any important information taken in during the course of the previous day.

During slow wave sleep, the hippocampus the section of the brain most associated with memory stops encoding new information and effectively closes down. At the same time, short-term memories stored in the hippocampus are relayed to other regions of the brain, where the memories are cloned and stored for long-term memory.

According to the National Sleep Foundation, a good night's sleep has a variety of health benefits, including promoting muscle relaxation and tissue growth. The Foundation recommends between seven and nine hours sleep per night for adults between the ages of 18 and 64. A 2014 study discovered the mechanism by which sleep improves learning and memory; new neural junctions between brain cells, known as synapses, are formed during sleep, and this increase in connections allows memories to be better retained and recalled.

Have a Good Night's Sleep to Help You Remember | Tech & Science