Sleep problems play an important role in the development and maintenance of many mental health issues, but the reason for this link is difficult to grasp. According to new research from the University of East Anglia (UEA), the link between poor sleep and mental health issues could be related to deficits in brain regions that keep unwanted thoughts at bay. The new study, published in Proceedings of the National Academy of Sciences (PNAS), offers new insights into the cognitive and neural mechanisms underlying the link between sleep and mental health. These findings could support the development of novel treatment and prevention strategies for mental health issues such as depression and anxiety.

Memories Can Influence Emotional Well-Being

Dr. Marcus Harrington, a lecturer at the UEA’s School of Psychology, is the lead author of the article ‘Memory control deficits in the sleep-deprived human brain’. He worked with colleagues at the universities of York, Cambridge, Sussex and Queen’s University (Canada). Using functional neuroimaging, they were able to show for the first time that memory control deficits after sleep deprivation are associated with difficulties in activating brain regions that support the inhibition of memory recall, and that the nightly rejuvenation of these brain regions is associated with REM (rapid eye movement) sleep.

Dr. Harrington said: “Memories of unpleasant experiences can surface into consciousness, often in response to reminders. ”While such intrusive memories are an occasional and temporary nuisance for most people, for those suffering from mental disorders such as depression, anxiety and post-traumatic stress disorder, they can be recurrent, vivid and disturbing. Because memories play a central role in our affective perception of the outside world, failures in memory control may go a long way toward explaining the link between sleep loss and emotional dysregulation.” According to the researchers, a better understanding of the mechanisms that trigger the occurrence of intrusive memories is essential to improving emotional well-being and reducing the global burden of mental illness.

Sleep Plays an Important Role in Maintaining Control Over Our Memories

85 healthy adults tried to suppress unwanted memories while images of their brains were taken using functional MRI. Half of the participants enjoyed a good night’s sleep in the sleep laboratory before the task, while the other half stayed awake all night. During memory suppression, the well-rested participants showed greater activation in the right dorsolateral prefrontal cortex – a brain region that controls thoughts, actions and emotions – compared to those who stayed up all night. The well-rested participants also showed less activity in the hippocampus – a brain region involved in memory retrieval – during attempts to suppress unwanted memories.

Among the participants who had slept in the laboratory, those who had spent more time in REM sleep were better able to activate the right dorsolateral prefrontal cortex during memory suppression, suggesting that REM sleep plays a role in restoring prefrontal control mechanisms that underpin the ability to prevent unwanted memories from intruding into consciousness. Taken together, these results underscore the critical role of sleep in maintaining control over our memories and ongoing thoughts, according to the researchers.