Receiving nitrous oxide after a traumatic event may help to reduce the incidence of distressing memories, suggests research published in Psychological Medicine.

Researchers tested 50 volunteers by having them watch graphic scenes from a violent film then split the participants into two groups: 50/50 nitrous oxide and air, or medical air.

Results showed that inhaling nitrous oxide after viewing the clips was linked to a much faster decline in the incidence of distressing memories. The day after viewing, the number of intrusions (involuntary, often distressing, memories that spontaneously come to mind after a distressing event) fell by 50%, and intrusions declined exponentially over the following week.

In contrast, the people who breathed normal air experienced a slower, more gradual and linear decline. A significant drop did not occur until day four.