It seems that researchers have identified a fundamental sleep mechanism that enables our brains to consolidate emotional memory. (Also, see here for the press release). During the course of the research, the investigators found that sleep spindles – bursts of activity that last for a second or less in specific stages of our sleep cycle – seem to be important for emotional memory. This is new: we already knew that sleep spindles were involved with information we recall about the world, things like people, places and events. However, the focus on emotional memory and sleep has previously been focused on the role of REM, or rapid eye movement sleep.
However, there is a cautionary note to this research. In the process of trying to partition the effects of sleep spindles and REM sleep on the recall of emotional memories, the researchers gave zolpidem, sodium oxybate and a placebo to 28 men and women who were normal sleepers. The study participants viewed images known to elicit positive and negative responses for one second before and after taking supervised naps. They recalled more images that had negative or highly arousing content after taking zolpidem. This suggests that the brain favoured the consolidation of negative memories. In fact, one of the researchers ventured that, “… sleep drugs might be improving memories for things they don’t want to remember.”
My concern for situations where people are anxious is that sleeping aids that may be prescribed may actually cause them to remember more negative memories than if they were not taking that medication. In circumstances where sleeping pill prescriptions have increased substantially, e.g. post-earthquake Christchurch, this doesn’t look like an outcome we should be aiming for. Granted, zolpidem isn’t quite the same as zopiclone – which I believe is the most widely prescribed sleeping pill in New Zealand – but this still raises alarm bells for me. I think I would agree with the investigators that it would be worthwhile investigating whether the administration of benzodiazapine-like drugs might increase the retention of arousing and negative memories. Many in Christchurch are taking this type of medication precisely to get relief from highly stressful life circumstances. It may be that they are unwittingly increasing the chances that they recall negative memories throughout their days as a result of taking this medication.