Can’t stop thinking about your ex? Playing sounds during sleep can help you forget bad memories

We all have things we’d rather forget, whether it be your ex-partner or a particularly embarrassing moment.

Now, researchers have found that playing sounds to people while they sleep can be used to help you forget bad memories.

The team, from the University of York, hopes the findings could pave the way for techniques to help weaken traumatic and intrusive memories. 

For the study, the team recruited 29 participants, who learned two overlapping pairs of words – for example David Beckham and bicycle as one pair, and bicycle and castle as the second pair.

When learning both pairs they also heard the word ‘bicycle’ being played aloud.

Participants then went to sleep and when they entered slow-wave – also known as deep – sleep, they were played the word ‘bicycle’ again.

Their memory was tested when they woke up.

Comparing performance to a control condition, where the associated sounds weren’t played during sleep, memory for one pair was boosted while they appeared to forget the association of the other pair. 

Dr Bardur Joensen, first author of the study, said: ‘Although still highly experimental at this stage, the results of our study raise the possibility that we can both increase and decrease the ability to recall specific memories by playing sound cues when an individual is asleep.

‘People who have experienced trauma can suffer a wide range of distressing symptoms due to their memories of those events.

‘Though still a long way off, our discovery could potentially pave the way to new techniques for weakening those memories that could be used alongside existing therapies.’

Previous research has found that learning a pair of words, and playing a sound associated with that pair during sleep, improved participants’ memory for the word pair when they woke in the morning.

But this is the first time they have shown a decrease in memory for a word pair, suggesting it is possible to cause selective forgetting by playing associated sounds during sleep.

Senior author Dr Aiden Horner said: ‘The relationship between sleep and memory is fascinating.

‘We know that sleep is critical for memory processing, and our memories are typically better following a period of sleep.

‘The exact mechanisms at play remain unclear, but during sleep it seems that important connections are strengthened and unimportant ones are discarded.’

The effect is likely to occur because of some form of competition between the overlapping memories, Dr Horner explained.

‘It might be possible to take one aspect of a previous real-world memory – for example a particular location where an event occurred – and associate that with a new event,’ he said.

‘If we could use the sound cues during sleep to selectively boost memory for this newly learned event, then this might have the effect of decreasing memory for the original event.’

The findings were published in the journal Learning & Memory.