For a test of memory where people are asked to remember a list of about 80 words, sleep can improve memory by a third or even up to 100%.
In the year 2000, the BBC moved its main news program from 9pm to 10pm responding to changes in people’s routines. Over the last 20 years the amount of sleep people are getting seems to be reducing at an alarming rate.
Sleep is vitally important for effective functioning in educational and work place settings – a good sleep ensures we have good levels of attention and concentration. The studies we have conducted at Lancaster show the importance of sleep for functions that are critical to performance in education or the workplace. But sleep is also an active process affecting what we have already learned and experienced, and reduced sleep will adversely affect the way in which our brain carries out these important functions. If you are scheduling revision sessions – make sure you include sleep.
In our lab in the Department of Psychology, we are investigating these positive effects of sleep, looking at improvements and changes in memory, in learning, and problem solving and creativity. We have found that sleep has a profound effect on all these tasks. To test the effects of sleep, we bring people into the lab and give them a test – such as memorising a list of words, learning some new words, or solving some brain-teaser problems. Then after either a sleep or staying awake, we retest to see if there are changes after sleeping that we do not see after staying awake.
When we see dramatically improved memory after someone has been asleep, this happens because the words that participants see are linked more thoroughly with long-term storage of these words in the brain. In one test of how people join together new information in memory – such as knowing about an object and also knowing you will find it in a particular location - we found that sleep improved performance by more than 100%.
These positive effects of sleep are also found for more complicated tasks, such as problem solving. For these we can also see up to a 100% improvement following sleep. We find the biggest improvements for more difficult problems. If you want to remember something, learn something new, or solve a problem, sleep on it.