New research from the University of York and the University of East Anglia reveals that sleep deprivation hampers the brain's ability to suppress intrusive memories, a crucial process for maintaining mental health. The study, published on January 8, 2025, highlights the importance of REM sleep in restoring this cognitive function.
The researchers found that well-rested individuals could engage the right dorsolateral prefrontal cortex to inhibit unwanted memories, while those who were sleep-deprived struggled significantly. Dr. Scott Cairney from the University of York noted, 'Memories of unpleasant experiences often intrude into our conscious mind in response to reminders, but tend to be fleeting and can be put out of the mind again. However, the brain's ability to suppress such intrusive memories is contingent on obtaining restful sleep.'
In their study, 85 healthy adults underwent functional magnetic resonance imaging (fMRI) scans. Half had a restful night’s sleep, while the other half remained awake. Participants were shown faces previously paired with emotionally negative scenes, such as a car crash. They were instructed either to recall or suppress the associated scenes.
The results showed that well-rested participants exhibited increased activation in the right dorsolateral prefrontal cortex—responsible for controlling thoughts, actions, and emotions—compared to their sleep-deprived counterparts. Additionally, they demonstrated reduced activity in the hippocampus during memory suppression attempts, indicating their ability to 'shut down' the retrieval processes that lead to intrusive thoughts.
Crucially, those who experienced more REM sleep were better at engaging the right dorsolateral prefrontal cortex, suggesting that REM sleep plays a vital role in restoring the brain's mechanisms for preventing unwanted memories from surfacing.
Dr. Cairney emphasized the implications for mental health, stating, 'This is really important to our understanding of mental health issues as it is well documented that those who suffer with anxiety, depression, or PTSD also have difficulty with sleep. Now that we have a better understanding of the mechanisms in the brain that can help restrict negative memories and thoughts, we can perhaps work on more targeted treatments and behavioral therapies that help with improving sleep.'