According to BBC News, a study has found that during sleep, the experiences a person cares about are more likely to enter their long-term memory.
Eighty non-Welsh speaking participants were taught Welsh words before either a period of wake or sleep.
Those who slept showed an increased ability to learn the words, and the effect was greatest in those who placed personal value on the language.
This suggests that memories perceived as important undergo preferential treatment by the brain during sleep.
While it has long been established that sleep helps the consolidation of memories, this is the first study to show that the effect is influenced by how much you care about the memory.
The findings were discussed on Friday at the British Science Festival and are soon to be published in the Journal of Sleep Research.
“The mere fact that your beliefs about something seem to affect how the brain processes things during the night is really quite astounding,” said Prof Mark Blagrove from Swansea University, who conducted the research with colleague Elaine van Rijn.
