Sleep could be a boost to our happiness by preserving our emotionally positive memories, a study has found.

Rebecca Spencer of the University of Massachusetts, Amherst, and her colleagues split 70 young adults into two groups – one that was allowed to sleep and one that had to stay awake.

The team of researchers presented the groups with positive images, such as puppies and flowers, and neutral items, like furniture or dinner plates, the Medical Express reports.

The groups were asked to rate the images and then tested on their memories of the pictures 12 hours later, after the period of sleeping or staying awake.

The memories of the positive images were found to be stronger among those who had slept.

Presenting the findings to a meeting of cognitive neuroscientists in Chicago, Spencer said sleep actually “enhances our emotionally positive memories while these memories decay over wake”.

“Positive memories may even be prioritised for processing during sleep,” she was quoted as saying by the Medical Express.

Past research has found that insomnia is a healthy biological response for people who have experienced some kind of trauma.

The latest study suggests that wakefulness may degrade the positive memories as much as it does the negative.

Spencer believes the findings could have significant implications for the treatment of post-traumatic stress disorder, allowing positive memories to be “strengthened” and “eventually outweigh the negative”.

She concludes that people should sleep to enhance their memories.

“For mildly negative memories, we can learn something from them and we should remember them,” she said.

“Moreover, sleep enhances memories for the positive events that we are exposed to and want to remember.”