Many people remember another person even if they have only seen them once. But there are times when we cannot recognize a new acquaintance or remember his name.
Scientists from Northwestern University in the United States figured out how the quality of sleep affects these memory properties. A new study has documented for the first time the impact of memory reactivation during sleep on remembering names and faces.
The study was conducted on 24 participants aged 18 to 31 who were asked to remember the faces and names of 40 students from a hypothetical Latin American history class and another 40 students from a Japanese history class.
When each face was shown again, they were asked to name the corresponding name. After the training exercise, the participants took a nap while the researchers carefully monitored their brain activity using EEG measurements (a recording of the electrical activity of the brain taken by electrodes on the scalp).
As the participants fell asleep, some of the names began to play softly through the speaker with music that was associated with one of the classes. The participants then woke up and were retested for face recognition and recall of the name that accompanied each face.
The experts found that people’s memory improved significantly when newly learned name associations were activated during sleep. The key to this improvement was uninterrupted deep sleep. People who had deep uninterrupted sleep at certain times of the audio presentations remembered an average of 1.5 more names. And for study participants with EEG measurements that indicated sleep disturbance, memory reactivation did not help and could even be harmful.
“This is a new and interesting discovery about sleep. We already know that some sleep disorders, such as sleep apnea, can impair memory. Our study offers a potential explanation for this. It turns out that frequent sleep disturbances at night can impair memory, ”said Nathan Whitmore, lead author of the study.