- People with type 2 diabetes, heart disease, or stroke who experienced better sleep quality performed significantly better on cognitive tests and had larger total brain volume, according to new research.
- Quality sleep may help protect brain health in cardiometabolic disease by reducing inflammation and supporting the glymphatic system, which clears metabolic waste from the brain during sleep.
- To help improve sleep quality, experts advise creating a darker sleep environment with blackout curtains and treating conditions that can disrupt rest.
Getting enough quality sleep could help improve cognitive function in people with type 2 diabetes, heart disease, or stroke, also known as cardiometabolic diseases (CMD).
This is according to a new major study published in November in the
The researchers examined over 400,000 people with and without CMD and found that better sleep among those with CMD led to improved performance in areas such as cognitive functioning and processing speed.
Those with CMD who experienced better sleep also had a larger total brain volume.
While this was an observational study and therefore cannot confirm a direct link between sleep quality and cognition, the findings suggest that good sleep quality may help reduce the effects of CMDs on the brain by supporting brain health and cognitive function.
Better sleep linked with higher cognitive test scores
People with CMD who had higher-quality sleep achieved higher scores on cognitive testing.
The researchers examined data from 408,977 adults in the UK Biobank, of whom over 50,000 had at least one CMD.
Sleep quality was assessed based on self-reported information that addressed:
- sleep duration
- chronotype
- insomnia symptoms
- snoring
- daytime sleepiness
The researchers also analyzed brain MRI scans from over 34,000 participants.
Compared with those with CMD and poor sleep patterns, individuals with CMD and healthy sleep patterns had a “significantly higher” performance in:
- global cognition
- verbal and numerical reasoning
- processing speed
The brain scans also showed “significantly larger” total brain, gray matter, and white matter volumes in those with CMD who had better sleep.
Alex Dimitriu, MD, double board certified in Psychiatry and Sleep Medicine and founder of Menlo Park Psychiatry & Sleep Medicine, spoke with Medical News Today about the study’s findings.
“This study reinforces the understanding that sleep is one of the most significant contributors to cognition and brain health,” said Dimitriu, who was not involved in the study.
“Good sleep was found to be a major protective factor in people with cardiometabolic disease, preserving processing speed, and, equally impressively, brain volume.”
—Alex Dimitriu, MD
Inflammation and glymphatic system function factors to consider
The researchers suggest that reduced inflammation and improved glymphatic system function during sleep could contribute to improved cognitive function in those with CMD.
They explain that sleep supports brain health by helping the glymphatic system, located in the central nervous system, clear metabolic waste such as amyloid-β.
Reduced sleep quality could also lead to chronic inflammation, which can reduce cognitive performance.
“This relationship is multifactorial but is thought to be related to poor sleep causing decreased clearance of beta-amyloid, a protein fragment associated with Alzheimer’s dementia when it accumulates in the brain,” Amit Blumfield, MD, cardiologist, with Manhattan Cardiology in NYC and contributor to LabFinder.com told MNT.
“Poor sleep is also related to higher rates of metabolic disease, diabetes, hypertension, and inflammation, all of which are associated with earlier cognitive decline and increased rates of dementia,” said Blumfield, who was not involved in the study.
(S)leep modulates the immune system and can reduce inflammation, which is not good in any part of the body, and especially in the brain, where it can lead to impaired healing, reduced cognition, and mood symptoms like depression,” Dimitriu explained.
How sleep resets the body
“The glymphatic system is like a power wash for the brain, which only happens at night. This clears numerous toxins and metabolic products from the second most energy-hungry organ in the body — our brain. Put more simply, sleep resets and restores the immune system, and power-washes the brain so it can operate most efficiently the next day.”
—Alex Dimitriu, MD
How to improve sleep quality with CMD
MNT spoke with Yu-Ming Ni, MD, board certified cardiologist and lipidologist at MemorialCare Heart and Vascular Institute at Orange Coast Medical Center in Fountain Valley, CA, about ways in which a person with CMD could improve sleep quality.
“I would create an environment that promotes good-quality sleep. If outside light enters your bedroom, blackout curtains or an eye mask are reasonable options. You can also dim the lights in the evening, turn off unnecessary lights, and limit bright screens before bed,” explained Ni, who was not involved in the study.
“The goal isn’t to create perfect darkness at all costs, but to minimize unnecessary light and make your sleep environment as comfortable and conducive to sleep as possible,” he added.
Blumfield explained that treating conditions that impact sleep is also important.
“Cardiometabolic disease is associated with sleep apnea, restless leg syndrome, and general insomnia, all of which impact sleep amount and quality. (…) Screening for and treating sleep apnea can tremendously improve sleep quality. Additionally, GLP-1 receptor agonists have also been shown to lower apneic events in patients with sleep apnea,” he said.
“Healthy sleep is increasingly recognized as an important part of cardiovascular health, and creating a darker sleep environment is a simple step that may support better sleep. Think of it as one smaller, potentially helpful habit rather than the key to preventing heart disease.”
—Yu-Ming Ni, MD
