Overview
We've all had sleepless nights, tossing, turning, and feeling foggy the next day. But beyond the familiar fatigue, lack of sleep has a hidden cost.
It may impair our ability to control intrusive thoughts and memories. A recent study explains how sleep deprivation alters essential neural mechanisms, exposing us to undesired and frequently emotionally charged memories.[1]
Keep reading to learn more about this fascinating study.
The Connection Between Sleep and Memory Control
Sleep and memory are linked. Research shows that a good night's sleep boosts short-term and long-term memory.[2] But, it isn't every memory that people want to remember. When unwanted memories intrude on our thoughts, they often cause emotional pain.
Thankfully, the human brain can suppress intrusive memories. This ability is a psychological safety net for most people, helping us maintain emotional balance.
However, if memory suppression fails, intrusive memories can worsen anxiety, depression, and PTSD.[3]
Experts have always believed that sleep is key to this complex memory system. However, the exact mechanism sleep does this isn't clear.
New evidence indicates that a well-rested brain activates the prefrontal cortex. It mainly relies on the right dorsolateral prefrontal cortex (rDLPFC).[4]
This area helps control memory retrieval processes in the hippocampus, the memory center. This suppression weakens the memory trace, making intrusive thoughts less likely to reappear. But what happens when we deprive the brain of this vital rest?
The Sleep Deprivation and Memory Control Mechanism Study
A brilliant new study by the University of East Anglia, published in the Proceedings of the National Academy of Sciences (PNAS), examined how sleep deprivation affects memory control and retrieval.[1]
The scientists recruited 85 healthy adults aged 18 to 30 for a series of tests. The participants were divided into two (2) groups. Forty-three (43) people were placed in the sleep-deprived group, and forty-two (42) were in the restful sleep group. Afterward, participants completed tasks in two rounds, one in the evening and one in the morning.
People who didn't get enough sleep stayed awake for 24 hours. The group that slept well rested for 8 hours, which a sleep study tracked. The memory control task includes:
- Think/No-Think (TNT) Task: Participants were shown pairs of cues and images. Some images were neutral, others negative. They had to either think about the image (Think trials) or suppress it (No-Think trials). They also reported their continuous thought patterns while completing the activity.
- Functional Brain MRI: The participants had a brain MRI. It measured brain connectivity while they viewed pairs of cues and images on the Think/No-Think (TNT) task.
- ECG Reading: After the individuals left the scanner, the researchers recorded an 8-minute resting ECG. It was to calculate heart rate variability (HRV). This step was included because past studies found a link between inhibitory control over cognition and the high-frequency component of heart rate variability on ECG.[5]
Here are the key findings the researchers noted after looking at all the data:
- Impaired Memory Suppression After Sleep Deprivation: Sleep-deprived subjects could not inhibit intrusive memories compared to the well-rested group. During memory suppression, the fMRI scans of sleep-deprived people showed less rDLPFC (right dorsolateral prefrontal cortex) engagement and weaker hippocampal disengagement.
- Disrupted Brain Network Connectivity: Sleep-deprived people had a disrupted connection between the default mode network (DMN), which is linked to internal thought, and the thalamus, which regulates arousal. This finding shows a problem with functional network segmentation.
- A Reduction in Focused, On-Task Thinking: Sleep-deprived participants showed a decrease in purposeful, task-focused thinking compared to those who slept, regardless of cognitive strain. If one can't suppress intrusive thoughts, it could lead to a less purposeful, fragmented mind.
- The Role of REM Sleep in Memory Suppression: Longer REM sleep was linked to higher rDLPFC activation during memory suppression. REM sleep replenishes prefrontal systems necessary for suppressing intrusive memories.
- A Heart-Mind Connection: The study found a link between memory control and heart rate variability (HRV). HRV shows how well the nervous system adapts to stress. Higher HRV in well-rested subjects was associated with improved memory suppression. However, this link reversed for sleep-deprived people. It implies that those who resist intrusive memories may be more prone to the effects of sleep deprivation.
A Broader Implication For Mental Health
The researchers noted that their study's results are significant for learning how sleep affects mental health. They said that memory control problems might cause unwanted thoughts and strong emotions in anxiety and PTSD.
Also, problems with REM sleep, which often occur in these disorders, can make it harder to manage memories and feelings.
What Does This Mean for You?
The study's findings serve as a wake-up call to improve sleep quality. Sleep is more than a passive state. It is an active process that helps our brains manage memories and emotions. Here's how you can improve your sleep to protect your memory and mental health:
- Prioritize Quality Sleep: Aim for 7-9 hours of uninterrupted sleep each night. Your brain needs this time to restore memory control mechanisms.
- Maintain a Consistent Sleep Schedule: Go to bed and get up at the same hour every day, even on weekends. This routine regulates your body's internal clock (circadian rhythm), improving the quality of your sleep.
- Optimize Your Sleep Environment: Make your bedroom calm, quiet, and dark. Use blackout curtains or drapes. Also, get a good mattress and pillows to help you sleep better.
- Watch What You Eat and Drink Close to Bedtime: Avoid caffeine and nicotine close to your bedtime. These stimulants can disrupt your ability to fall and stay asleep. Also, minimize alcohol consumption. It can fragment sleep and reduce REM sleep, which is vital for memory and mental health.
- Manage Stress and Anxiety: Try deep breathing, progressive muscle relaxation, and mindfulness meditation. These methods help you relax. Also, consider keeping a notebook to sort your thoughts before bed.
The Takeaway
Next time you're tempted to pull an all-nighter, remember that your brain needs sleep as much as your body. Without it, the delicate neural mechanisms that keep your thoughts under control may begin to fail, leaving you vulnerable to unwanted memories and mental problems.
References
- Harrington, M. O., Karapanagiotidis, T., Phillips, L., Smallwood, J., Anderson, M. C., & Cairney, S. A. (2025). Memory control deficits in the sleep-deprived human brain. Proceedings of the National Academy of Sciences of the United States of America, 122(1). https://doi.org/10.1073/pnas.2400743122
- Paller, K. A., Creery, J. D., & Schechtman, E. (2021). Memory and Sleep: How Sleep Cognition Can Change the Waking Mind for the Better. Annual review of psychology, 72, 123–150. https://doi.org/10.1146/annurev-psych-010419-050815
- Brewin, C. R., Gregory, J. D., Lipton, M., & Burgess, N. (2010). Intrusive images in psychological disorders: characteristics, neural mechanisms, and treatment implications. Psychological review, 117(1), 210–232. https://doi.org/10.1037/a0018113
- Benoit, R. G., Hulbert, J. C., Huddleston, E., & Anderson, M. C. (2015). Adaptive top-down suppression of hippocampal activity and the purging of intrusive memories from consciousness. Journal of cognitive neuroscience, 27(1), 96–111. https://doi.org/10.1162/jocn_a_00696
- Harrington, M. O., Ashton, J. E., Sankarasubramanian, S., Anderson, M. C., & Cairney, S. A. (2021). Losing Control: Sleep Deprivation Impairs the Suppression of Unwanted Thoughts. Clinical psychological science : a journal of the Association for Psychological Science, 9(1), 97–113. https://doi.org/10.1177/2167702620951511