Dreams may help us remember things we value, study suggests

Dreams appear to help people remember facts they value better than those they do not, according to a new study which adds weight to the theory that the sometimes bizarre imagery has a deeper purpose.

The reasons why people dream are still controversial. According to some experts, they are just random noise as the brain takes a rest.

But others believe they are actually part of the process of filing newly acquired knowledge and memories and an important way of coping with traumatic events.

In a study at Swansea University Sleep Laboratory, participants were taught Welsh phrases and then tested on how much they could remember.

Those who got a good night’s sleep fared better than those who learned the words in the morning and were tested later that day.

But people who placed a particular value on the Welsh language got more of a benefit from sleeping on what they had been taught.

The researchers have also found that the so-called ‘dream lag’ effect — in which people will dream about something and then have a similar dream up to a week later — is more likely to happen if the event is personally significant.

Speaking ahead of a presentation at the British Science Festival, sleep researcher Professor Mark Blagrove described the effect of sleeping — and possibly dreaming — on the Welsh language students.

“On average they improved more than people who learned it in the morning and were tested in the evening,” he said.

“And the amount of improvement was related to their valuing of the material. The more they valued the language, the more they learned.

“That ties in with the other work we’re doing on dreaming because what we’ve been finding is that you tend to dream of emotional things that have happened to you.”

When people dream about real-life events, they tend to be about things that happened during the day.

“If you dream of important things that happen in the day, it maybe just a residual consequence of things that happened to be in your mind and nothing of any consequence at all,” Professor Blagrove said.

But sometimes the issue can recur in what is usually a more abstract dream between five and seven days later.

This dream lag effect, the academic said, “does seem to be evidence in favour of dreams showing you something important that your brain is doing”.

“That’s very difficult to explain except the brain is doing something over that time period,” he said.

It is thought this could be a way of matching new memories to old ones as they are transferred to the long-term memory.

The later dreams are also more metaphorical. So much so that while the dreamers were able to say they were about something that happened a week ago, independent judges given transcripts of the dreams and a diary of daily events were unable to match them to the real world event.

There are also conflicting views on nightmares. It is possible they are actually beneficial.

But Professor Blagrove added: “There’s a claim that the dream is trying to put things together and a nightmare occurs if you fail.

“It’s trying to do something with a really bad trauma and just cannot do the linking and interconnecting … and cannot make sense of things.

“That’s used to explain why a trauma will recur in dreams and it’s not made into a kind of metaphor in which you start to make sense of things.”

He said it was common to forget dreams — and this might be a good thing.

“It could be we have evolved to forget them very quickly. It could be it’s best not to know.”