Sleepless nights can increase your chances of forming false memories, according to researchers in Germany and Switzerland. But, as for so many aspects of life, it seems that coffee can save the day. Although neuroscientists know that memories can be strengthened while we are asleep, it’s been unclear whether false memories form as we slumber or whether they are only consolidated when we are asked to recall the information the following morning. To find out, Susanne Diekelmann in Jan Born’s lab at the University of Lübeck, Germany, and her colleagues asked volunteers to learn lists of words, each list relating to a particular topic. For example, they might learn the words ‘white’, ‘dark’, ‘cat’ and ‘night’ — all of which can be linked to the word ‘black’ — but black itself would not be part of the list.
The researchers then tested their subjects’ memories after a night’s sleep or a night spent awake. They showed them the list of words again, having added a few extra words, and asked them to recall whether the words had been in the original list. The sleep-deprived group gave more false responses than the group allowed to sleep. “A lot of subjects said, ‘yes, these false words were presented before’, and they were absolutely sure about it,” says Diekelmann. “Sometimes they were even more convinced than on the real words.” Diekelmann suggests that it isn’t sleep deprivation itself that causes the formation of false memories, but the act of retrieving them from storage.