Maybe you watched a loved one pass away recently. Or maybe you were once mugged. Or maybe you witnessed a really horrendous car accident on your way to work last week.

After going through a traumatic experience like that, feeling tense with anxiety, sadness or fear, you might want to bury your head into your pillow and just sleep—just to stop thinking about it. But a new study shows that doing the exact opposite may help you get past the trauma.

To find out why, I called study author Rebecca Spencer, PhD, an assistant professor of psychology at University of Massachusetts at Amherst.

TO SLEEP, PERCHANCE TO…RELIVE

Dr. Spencer and her team conducted a very clever study, so I want to take a minute to describe it to you. They showed 106 adults a series of images. Half of the images were classified as “emotionally neutral,” such as a person reading the newspaper, while the other half were categorized as “disturbing,” because they were of such scenes as a war-torn country or a person with a gun held to his or her head. Participants were asked to rate their feelings about each image on two scales. One scale measured sad versus happy, and the other scale measured calm versus excited. “Excited” was used to describe any strong reaction, whether positive or negative.

Participants saw and rated each image twice—either first thing in the morning and then again that same evening, with no napping or sleeping in between…or first in the evening and then again the next morning after having slept through the night.

During their second sessions, both groups were also shown some images that they had not seen during the first sessions and were asked whether or not they thought they had seen them before.

Members of the “sleep group” wore electrodes on their scalps, chins and the outer edges of their eyelids while sleeping. The idea was to see how much time they spent in rapid-eye-movement (REM) sleep, which is when dreams tend to occur, because researchers were curious to learn whether dreaming might affect the emotional intensity of memories, Dr. Spencer told me.

The results: Those who did not sleep between viewing sessions were less likely to feel “sad,” on average, about photos that depicted negative events during the second session, compared with those who slept between sessions. Participants who did not sleep between viewing sessions also tended to feel more “calm,” on average, about the disturbing images the second time around, compared with those who slept between sessions. Some of the nonsleeper group even struggled to remember whether they had viewed the images 12 hours earlier.

Meanwhile, participants who had slept in between viewings were more likely to have remembered which images they had seen, and those who had spent the most time in REM sleep reacted with more emotional intensity to the “disturbing” images than they had done 12 hours before. In other words, seeing and thinking about these images proved more disturbing to them even though they had gotten a “good” night’s sleep! Dr. Spencer’s research was published in January in Journal of Neuroscience.

HOW THE IMAGES AND EMOTIONS ARE PROCESSED

Dr. Spencer and I discussed how the amygdala, a region of the brain that is responsible for helping us “replay” memories of daytime experiences likely solidifies them during REM sleep. What this study suggested, she said, is that the amygdala also “replays” theemotional tone of those experiences in a way that leaves us feeling them more vividly. So seeking to immediately “sleep off” the impact of a traumatic emotional event actually may be the worst thing that we can do for ourselves, she said—instead of softening the blow, it imprints the memory even deeper.

In Dr. Spencer’s view, if you experience something really terrible, limiting yourself to either no sleep or just a few hours of sleep during that first night—and even limiting how much you sleep during the following few days—may help you heal better, emotionally, down the road.

The researchers unfortunately didn’t measure how sleeping, say, two or three or four days after a traumatic experience impacts the emotional intensity of a memory, but this study suggests that those who put off sleeping for at least 12 hours after the experience are better off than those who go to bed sooner. As Dr. Spencer put it, “This is one case where insomnia may actually be a healthy response.”

Source: Rebecca Spencer, PhD, assistant professor, psychology, University of Massachusetts Amherst.