A good night's sleep may be the wrong thing to suggest to someone who has experienced a traumatic event, according to a recent study.

Researchers at the University of Oxford found that sleep deprivation might prevent people from consolidating memories of experimental trauma, reducing their tendency to experience flashbacks.

"We wanted to see what effect sleep deprivation would have on the development of intrusive memories -- what in a clinical setting re called flashbacks," researcher Dr. Kate Porcheret  said in a statement.

For the study, Porcheret showed study participants a film of scenes with traumatic content, as an analogue to trauma. They were then either kept in a sleep laboratory and deprived of sleep or sent home to have a normal night's sleep in their own bed.

Each person kept a diary in which they recorded any intrusive memories, however fleeting, recording as much information as possible so that the research team could check that the intrusive images were linked to the film.

According to researcher Dr. Katharina Wulff, "the sleep-deprived group experienced fewer intrusive memories than those who had been able to sleep normally. Both groups experienced more of these involuntary memories in the first two days and a reducing number in the following days. We know that sleep improves memory performance including emotional memory, but there may be a time when remembering in this way is unhelpful."

However, researchers said more research is needed to find out more about how sleep and trauma interact. There is currently limited understanding of intrusive memories of emotional events as well as of the role of sleep in responding to real trauma.

The findings are detailed in the journal Sleep.