People suffering from post-traumatic stress disorder (PTSD) often struggle with intrusive and distressing memories. A recent study published in Proceedings of the National Academy of Sciences may shed light on why these individuals find it difficult to suppress unwanted recollections.

Researchers have discovered that sleep deprivation significantly disrupts the brain’s ability to regulate memory retrieval, making it harder to suppress distressing memories. The study, led by Scott Cairney, an associate professor of psychology at the University of York in England, highlights the critical role of sleep in mental health and memory management.

“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,” Cairney explained in a news release.

To examine the connection between sleep and memory suppression, the research team conducted an experiment involving 85 healthy adults. Half the participants spent a night in a sleep lab, while the other half remained awake all night. Using MRI scans, researchers observed participants’ brain activity as they attempted to suppress memories associated with distressing images.

The results were striking. Participants who had a full night’s rest displayed increased activity in the right dorsolateral prefrontal cortex—a brain region responsible for controlling thoughts, emotions, and actions. They also showed reduced activity in the hippocampus, the brain’s primary memory center, when attempting to suppress intrusive memories. In contrast, sleep-deprived participants struggled to engage these critical brain regions, leading to a diminished ability to suppress unwanted recollections.

“Suppression is a very clever function of the brain,” Cairney noted. “It weakens all of the connecting traces of the memory, inhibiting us from joining up all the dots to retrieve the full picture of the experience when it is triggered by an external stimulus.”

Rapid eye movement (REM) sleep, a phase associated with dreaming and memory consolidation, was also linked to improved memory control. Participants who experienced more REM sleep were better able to activate the brain regions necessary for suppressing intrusive thoughts, researchers said.

The study underscores the importance of sleep in maintaining mental health and managing negative memories. It suggests that targeted treatments or behavioral therapies aimed at improving sleep quality could help individuals with PTSD and other mental health conditions suppress distressing memories more effectively.

“Now that we have a better understanding of the mechanisms in the brain that restrict negative memories and thoughts, we can work on developing more targeted interventions,” Cairney concluded. “By supporting the brain’s natural abilities, we can help people lead mentally fit lives.”

The findings highlight the intricate connection between sleep, memory, and mental health, offering a promising avenue for future research and therapeutic advancements.