Insomnia Isn’t Just Exhausting — It May Raise Your Risk Of Stroke, Dementia

• A recent review has found that insomnia may be associated with an increased risk of stroke and hospitalization.
• The researchers also found evidence of an association between insomnia and depression, suicidal behaviors, and dementia. 
• These findings add to growing evidence that insomnia may be linked to health risks beyond poor sleep and impaired daytime functioning.

Insomnia may do more than leave you tired. A review published in Sleep Medicine Reviews on September 7 has linked it to a higher risk of stroke, depression, and hospitalization.

Insomnia is characterized by difficulty falling or staying asleep despite having an adequate opportunity to sleep and typically involves impaired daytime functioning.

“Sleep is such an important health factor when we think about overall well-being,” Joseph You, MD, cardiologist with Manhattan Cardiology in NYC, who wasn’t involved in the study, told Healthline.  

He noted that sleep deprivation and poor-quality sleep have long been linked to adverse cardiovascular events and other health problems.

Insomnia linked to 26% higher stroke risk

Insomnia is the most common sleep disorder in adults. Chronic insomnia affects approximately 22% of the general population.

“Chronic insomnia is generally characterized by ongoing sleep difficulty despite having an adequate opportunity to sleep, rather than simply having an occasional bad night,” noted Christopher Yi, MD, board certified vascular surgeon at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, who wasn’t involved in the study. 

To examine the association between insomnia and stroke, the researchers identified nine studies involving more than 1.3 million people. Six were included in the meta-analysis, which found that insomnia was associated with a 26% higher risk of stroke.

It is important to keep in mind that association does not equal causation. However, several factors may help explain the link between insomnia and stroke.

Persistent sleep disruptions can trigger overactivation of the sympathetic nervous system. 

The sympathetic nervous system is part of the body’s involuntary nervous system that triggers your “fight or flight” response in stressful or dangerous situations.

“Being too wired can impair sleep, and impaired sleep, in turn, can make us too wired. A state of higher adrenaline and cortisol raises blood pressure, blood sugar, and increases inflammation, all of which have serious health effects,” said Alex Dimitriu, MD, double board certified in Psychiatry and Sleep Medicine, and founder of Menlo Park Psychiatry & Sleep Medicine, who wasn’t involved in the study. 

The review authors noted that these changes can not only raise blood pressure and heart rate but can also increase vascular tone while reducing heart rate variability. Continuous cortisol release can also promote hypertension, systemic inflammation, and disrupt glucose and lipid metabolism. 

Together, these changes may promote plaque formation and compromise vascular health, potentially contributing to a higher risk of stroke.

“I would emphasize that this study demonstrates an association and does not prove that insomnia directly causes stroke or other cardiovascular events,” cautioned Yi.

“There was significant variability among the studies, and factors such as underlying medical conditions and the use of sleep medications could influence the results. The authors themselves caution that an independent causal role for insomnia has not been established.”

Insomnia can increase the risk of hospitalization by 28%

The researchers also looked at five studies examining the association between insomnia and hospitalization. The studies included mostly older adults and ranged in size from 1,101 to 484,707 participants.

Three of the studies, involving 19,745 participants, were included in a meta-analysis. Researchers found that people with insomnia had a 28% higher likelihood of hospitalization for any reason.

The researchers noted that insomnia may be a key marker of poor health and may exacerbate the severity of underlying health conditions.

People with insomnia may be more likely to have depression

The researchers reviewed six meta-analyses examining the association between insomnia and depression and other mental health disorders.

Although most were rated as having low or critically low methodological quality, the findings consistently linked insomnia with a higher risk of depression.

According to the researchers, chronic insomnia can lead to daytime fatigue, attention issues, and reduced executive functioning. These factors can increase rumination, negative thinking, and maladaptive coping strategies, which are all risk factors for depression and anxiety.

Separately, two meta-analyses found that insomnia was associated with a higher risk of suicidal ideation, suicide attempts, and suicide death.

Sleep disturbances are among several risk factors for suicide, including independently of depression.

This isn’t to say that insomnia causes depression or suicidal behaviors, only that it may be one among various risk factors.

Insomnia linked to higher risk of dementia

The researchers reviewed five meta-analyses examining the association between insomnia and dementia. The analyses included between 5 and 39 studies and ranged from 36,005 to more than 3.1 million participants, with follow-up periods ranging from 2 to 40 years.

Overall, most of the analyses linked insomnia with a higher risk of dementia. Three also found that insomnia was associated with a higher risk of Alzheimer’s disease.

The researchers noted several possible explanations for the association. Sleep disturbances may contribute to inflammation and impaired clearance of substances such as amyloid-beta and tau from the brain, processes that could potentially contribute to neurodegeneration.

However, these findings show an association between insomnia and dementia and do not establish that insomnia causes dementia.