It’s no secret that sleep plays an integral role in our health and wellbeing. A good night’s sleep can be the difference between a groggy, stressful day and an energetic, successful day. While sleep can certainly impact your mood, it is also important for the formation and retention of new memories.
Retaining new memories – known as memory consolidation – is associated with sudden bursts of oscillatory brain activity, called sleep spindles. New research published in Current Biology has found that sleep spindles also play an important role in strengthening new memories when newly learned information is played back to a person as they sleep.
“While it has been shown previously that targeted memory reactivation can boost memory consolidation during sleep, we now show that sleep spindles might represent the key underlying mechanism,” says Bernhard Staresina of the University of Birmingham in the UK. “Thus, direct induction of sleep spindles – for example, via transcranial electrical stimulation – perhaps combined with targeted memory reactivation, may enable us to further improve memory performance while we sleep.”
Sleep spindles are bursts of brain activity that last between a half second and two seconds, and measure in the 10-16 Hertz range on an EEG. They occur during non-rapid eye movement in sleep stages two and three. Past studies have found that the number of spindles a person experiences during the night could predict the individual’s memory the next day. In animals, studies have shown that sleep spindles are linked to the process through which the brain makes new connections.
Researchers from the United Kingdom postulated that experimental reactivation of memories might be linked to an increase of sleep spindles in the brain of a sleeping person. To test this theory, they ran an experiment in which participants learned to associate particular adjectives with specific objects and scenes. Some participants then took a 90-minute nap following their study session, while other participants remained awake. While the napping participants slept, the researchers cued those associative memories and unfamiliar adjectives.
The results showed that memory cues led to an increase in sleep spindles. By using the EEG while participants slept, the researchers were able to see that the EEG patterns during spindles related to the types of memories, either objects or scenes, that were being processed. Overall, these findings are evidence of the important information-processing role of sleep spindles in memory consolidation.
“Our data suggest that spindles facilitate processing of relevant memory features during sleep and that this process boosts memory consolidation,” says Staresina.
The implications of this study are far-ranging. We may now be able to further explore the processes that hold people back with learning disabilities, while also improving the processing of important information and memory for the general public.