Poor sleep makes your brain more vulnerable to intrusive thoughts

Here’s why bad sleep and toxic thinking go hand in hand

Written by Rachel Nuwer Edited by Gary Stix

Imagine you’re at a friend’s housewarming party and you spill red wine on their brand new white couch in front of everyone. You are so frustrated that every time you see your friend afterwards, you immediately think of the accident on the couch.

Research shows that how you react to those bad memories depends on how much sleep you get. If you get enough rest, your brain can quickly suppress negative memories. However, if you are someone who suffers from insomnia, intrusive thoughts about what happened, and the accompanying unpleasant feelings, will continue to haunt you for some time.

New research is now being published Proceedings of the National Academy of Sciences We provide insight into what exactly happens in a sleep-deprived brain when unwanted thoughts like this invade. “This could be an important piece of the puzzle in understanding why people who are chronically sleep-deprived are at higher risk of developing mental health problems,” said a researcher at the University of York in the UK. says Scott Cairney, associate professor of science. and senior author of the findings.

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Cairney and his colleagues have shown in previous research that sleep deprivation impairs people’s ability to inhibit unwanted thoughts. But the team “wants to take” these behavioral observations “a step further,” he says. “What’s actually going on inside, in the brain, when people aren’t getting enough sleep?”

Previous research has shown that the hippocampus is involved in retrieving memories of past events, and that another part of the brain, the right dorsolateral prefrontal cortex (rDLPFC), is involved in suppressing the retrieval process. Proven. Cairney and his colleagues hypothesized that sleep deprivation impairs the rDLPFC’s ability to “interrupt” search processes.

To test this, the researchers recruited 85 students. First, the researchers trained the subjects to associate images of neutral faces with specific scenes, including negative scenes such as car crashes and fights. “There are rich connections between faces and scenes, so when you show a face alone, their brains automatically begin a search process,” Cairney says.

Next, the researchers divided the participants into two groups. One group was allowed to stay awake all night, while the other group was allowed to sleep in beds in the lab. Participants in the latter group were monitored for the amount of time they spent in rapid eye movement (REM) sleep and non-REM sleep.

In the morning, all participants were shown images of previously trained faces, but this time they had to think about or suppress the memories they had been trained to associate with the faces. Throughout this work, brain activity was measured using a functional magnetic resonance imaging (fMRI) scanner.

The results confirmed Cairney and his colleagues’ hunch. Compared to participants who slept, participants who stayed awake all night had significantly reduced rDLPFC activity during times when they were supposed to be suppressing intrusive thoughts. Conversely, hippocampal activity may have increased because rDLPFC did not stop the retrieval process it was engaged in. The findings showed that sleep deprivation does not cause a general decline in brain activity, but rather appears to have a specific effect on sleep deprivation, Cairney said. Specific parts of the brain involved in executive functions.

The researchers also found that among participants who had slept the night before, there was a significant positive correlation between time spent in REM sleep and rDLPFC activity, especially when working on a memory suppression task. . “This is interesting because many disorders associated with debilitating intrusive thoughts, such as depression and PTSD, are also associated with disorders of REM sleep,” Cairney says.

This “interesting” new study suggests that REM sleep may play an important role in maintaining proper memory control, says researchers at the University of Kent, UK, who were not involved in the study. Cognitive psychologist Zara Bergström says: However, he added that “future studies will need to directly manipulate REM sleep” to determine whether REM sleep has a causal role in memory and thought control.

Maria Wimber, a cognitive neuroscientist at the University of Glasgow who was also not involved in the study, added that the new findings “have real potential to inform therapeutic approaches”.

“Interventions that enhance REM sleep could be part of treatments for disorders characterized by intrusive memories, such as post-traumatic stress disorder,” she says. This type of response may also be attempted in response to acute trauma. This is a possible preventive measure to ensure that toxic memories and flashbacks do not appear at all.