Study Objective: Our study sought to investigate the role of nocturnal sleep duration for the retrieval of oversleep consolidated memories, both prior to and after being cognitively stressed for ~30 minutes the next morning.
Sleeping enough protects the long-term memory against stress, says a small Swedish study published in “Sleep”. According to the study’s authors, when participants slept too little and were then subjected to stressful situations, they achieved lower scores in subsequent memory tests.
For the study, the researchers at Uppsala University had the 15 young adult male participants learn the locations of 15 card pairs on a computer screen, after which they were able to sleep eight hours in one session and four hours in another. The following morning, the subjects were asked to recall as many card pair locations as possible. Initially, there was no difference between test scores, showing that the half night’s sleep had no impact on the participants’ performance in the test.
However, after the participants were subjected to a stressful situation for 30 minutes – for example by having to recall a newly learnt list of words while exposed to noise – and then tested again, those who had only slept half a night recalled about 10 per cent fewer card pairs than those who had had eight hours of sleep and performed as well as before the stress situation.
“Our findings indicate that eight hours of sleep, as recommended by many experts, do not only promote memorizing of newly learned information, but also facilitate accessing the long-term memory in stressful situations, as they can occur in the job or in exams,” said study leader Christian Benedict.
Conclusion: Our findings suggest that 8-h sleep duration, within the range recommended by the US National Sleep Foundation, may not only help consolidate newly learned procedural and declarative memories, but also ensure full access to both during periods of subjective stress.