Having trouble sleeping can affect more than simply how well-rested someone feels in the morning. While having an occasional bad night’s rest is not uncommon, insomnia can impact many areas of life, including concentration and memory.
Existing research connects insomnia to conditions such as psychiatric illness, but the way it influences a broader range of health outcomes is unclear. This led a European research team to examine how insomnia affects multiple aspects of health.
The team found several associations between insomnia and different health conditions, including stroke, but could not establish that insomnia causes these conditions.
The review is published in Sleep Medicine Reviews.
Millions of people experience sleep disorders, including sleep apnea and restless leg syndrome. The most common sleep disorder is insomnia, which makes it hard to fall asleep or stay asleep.
A 2022 review estimated that around 10% of adults have insomnia disorder, and another 20% experience occasional symptoms.
Doctors diagnose chronic insomnia when it both affects daily functioning and occurs at least 3 nights per week for 3 months or longer. Some treatment options include cognitive behavioral therapy for insomnia (CBT-I) and prescription medications.
To learn more about how insomnia may impact long-term health outcomes, the research team conducted an umbrella systematic review. They searched the MEDLINE and EMBASE databases for reviews that examined whether insomnia was linked to dementia, stroke, depression, and suicide-related outcomes.
The team also conducted new systematic reviews on stroke, workplace injuries, and hospital admissions because none of the other reviews had meta-analyses on these outcomes.
For stroke, the researchers identified 9 studies with more than 1.3 million participants and combined results from 6 of them in a meta-analysis. They also evaluated three studies examining hospital admissions.
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The stroke analysis found that people with insomnia had a 26% higher relative hazard of stroke. The hospitalization analysis found 28% higher odds of admission for any reason.
The 26% increase compares the stroke risk between people with and without insomnia. It does not mean that 26% of people with insomnia will have a stroke.
They also found associations between insomnia and dementia, depression, and suicide-related outcomes. However, the researchers did not find an association between insomnia and mortality.
The researchers could not draw a firm conclusion about workplace injuries. They found only two studies and could not combine their results in a meta-analysis.
The authors emphasized that the findings do not prove causation. They said the review shows that insomnia may signal increased health risks, but it cannot establish whether it causes these conditions.
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The researchers noted that differences in how the included studies defined insomnia, as well as factors such as the use of sleep medication, may have affected the findings.
The authors recommend that clinicians ask about insomnia when evaluating a person’s neurological and mental health.
Christopher Yi, MD, a board certified vascular surgeon at MemorialCare Orange Coast Medical Center, who was not involved in the review, discussed the review findings with Medical News Today.
“This review adds to growing evidence that chronic insomnia may be an important marker of long-term cardiovascular health,” said Yi.
Yi described some of the possible mechanisms behind the correlation between insomnia and stroke.
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“Chronic insomnia can keep the body in a state of increased stress or hyperarousal,” explained Yi. “Over time, this may contribute to higher blood pressure, inflammation, arterial stiffness, and dysfunction of the blood vessel lining.”
“Insomnia should not simply be dismissed as a problem with sleep,” said Yi. “Persistent insomnia can affect overall health and quality of life, and it may be a signal that other health issues need attention.”
Yi recommended addressing chronic insomnia and traditional cardiovascular risk factors together.
Jagdish Khubchandani, PhD, MPH, a public health professor at New Mexico State University, who was also not involved in the review, also spoke with MNT about the review findings.
“This is a relative risk comparing people with and without insomnia. If all else remains the same in people, someone with insomnia has a 1.26-times higher chance of suffering a stroke compared to someone without insomnia.”
— Jagdish Khubchandani, PhD, MPH
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Khubchandani noted that absolute risk for strokes and other health issues may depend on the individual.
He also said that the review underscores the need to develop better measures of sleep problems, since many studies rely on self-reported sleep behaviors.
For clinicians, Khubchandani recommended using chronic insomnia as an opportunity to assess broader health concerns.
“This would include comprehensive cardiovascular and metabolic disease screening and management,” shared Khubchandani.
