A sleep disorder affecting over a third of Americans, equating to around 70 million individuals, has been linked to a significant increase in the likelihood of developing various health issues, including obesity, heart disease, and dementia.

A notable study from the Mayo Clinic recently revealed a 40 percent higher risk of dementia, symbolizing 3.5 years of accelerated brain aging, yet the harmful effects of insomnia stretch well beyond neurological concerns.

Insomnia significantly contributes to the onset and exacerbation of conditions such as high blood pressure, heart disease, stroke, obesity, and type 2 diabetes, while also weakening the immune system, making individuals more susceptible to infections.

The primary symptoms of insomnia include trouble falling asleep, difficulty staying asleep, waking up too early, or being unable to return to sleep after waking.

This widespread impact stems from sleep being crucial for biological maintenance and repair. When chronic insomnia disrupts this necessary restoration, it leads to hormonal imbalances, increased inflammation, and cellular damage.

This chain reaction burdens the cardiovascular system, alters metabolic processes, and weakens the body’s essential defenses, making chronic insomnia a significant yet alterable risk factor for several major diseases in the United States.

Sleep is also crucial for overall brain health. Drifting off at night initiates a cleaning process to discard waste and toxins the brain has accumulated while awake.

The brain cannot complete this core process during wakefulness, which allows toxins like inflammatory markers and proteins linked to Alzheimer’s and other dementias to accumulate, potentially leading to atrophy in parts of the brain that govern memory, executive functioning, and movement.

Dementia  

A long-term study of adults aged 50 and older, with an average age of 70, has linked chronic insomnia to accelerated cognitive decline and an increased risk of dementia. 

The research, analyzing data from the Mayo Clinic Study of Aging, found that individuals with chronic insomnia were 40 per cent more likely to develop mild cognitive impairment or dementia. 

Their brains also exhibited signs of accelerated aging, comparable to being nearly four years older.

The study associated insomnia with tangible biological damage, including a greater accumulation of Alzheimer’s-related proteins. 

Insufficient sleep is known to impede the clearance of amyloid-beta, leading to plaque buildup, and can increase levels of tau, a protein that forms toxic tangles. 

For carriers of the APOE4 gene, a known genetic risk factor for Alzheimer’s, chronic insomnia led to even steeper declines in cognitive function. Roughly 20 to 25 percent of Americans carry one copy of this gene, while 2 per cent carry two. 

These findings suggest that chronic insomnia may act as both an early warning sign and a potential contributor to future cognitive impairment, underscoring its significant impact on long-term brain health.

The research was published in the journal Neurology.

Heart disease

When the body is consistently deprived of adequate sleep, it enters a state of heightened stress.

The body overproduces cortisol, a hormone that, in chronic excess, keeps the body in a constant ‘fight-or-flight’ mode, which raises heart rate and blood pressure, putting undue strain on the heart.

Sleep is also crucial for regulating the immune system. Without it, the body produces an excess of inflammatory cytokines, proteins that play a role in immune response. This creates a state of persistent, low-grade inflammation throughout the cardiovascular system.

Together, high cortisol and chronic inflammation damage the smooth, protective lining of blood vessels. This is the primary driver of atherosclerosis, a process where plaque, made of fat, cholesterol, and other substances, builds up inside the arteries, hardening and narrowing them. 

Hardened, narrowed arteries greatly increase the risk of heart attack, stroke, and other cardiovascular diseases.

An estimated 121.5 million American adults, nearly 49 per cent, have some form of heart disease, including coronary artery disease, heart failure, and stroke. 

High blood pressure 

A key function of sleep is to give the cardiovascular system rest. 

In a well-regulated body, blood pressure follows the body’s sleep-wake rhythm, dipping significantly during the night. The dip allows the heart to work less vigorously and the walls of blood vessels and arteries to relax. 

When sleep is disrupted or cut short, this vital dip does not occur. As a result, the heart and blood vessels are forced to operate at daytime pressure levels for 24 hours a day, placing them under non-stop stress. 

The constant pressure is a major contributor to the long-term development of hypertension, or high blood pressure, and cardiovascular disease. 

Around 115 million adults, nearly half of the population, has high blood pressure. 

Weight gain and obesity 

Insomnia and sleep deprivation disrupt key hormones that regulate appetite, including an increase in ghrelin, the hormone that stimulates hunger, and a decrease in leptin, the hormone that signals satiety. 

The resulting hormonal imbalance directly leads to increased feelings of hunger and a reduced sense of fullness.

Beyond this shift, sleep loss also affects neurological reward pathways. It amplifies the perceived pleasure and reward value of high-calorie, carbohydrate-dense, and fatty foods, influencing poorer dietary choices.

Insufficient sleep is also interpreted by the body as a stressor, elevating levels of the stress hormone cortisol. 

This stress response further promotes cravings for comfort foods, which are often energy-dense or ultra-processed, creating a compounded effect that significantly increases the likelihood of overeating. 

Approximately 40 per cent of American adults are obese, equating to around 100 million individuals. That number has steadily risen in recent decades as food has become more and more processed and Americans have become more sedentary. 

Type 2 Diabetes

Insufficient or poor-quality sleep hinders the body’s ability to regulate blood sugar, promoting the development of insulin resistance, a primary risk factor for type 2 diabetes. 

Sleep deprivation reduces the body’s sensitivity to insulin, the hormone essential for transporting glucose from the bloodstream into cells for energy.

To compensate for this reduced sensitivity, the pancreas must produce greater amounts of insulin to maintain normal blood sugar levels. This increased demand places strain on the pancreas over time. 

Poor sleep can elevate inflammation throughout the body. Both weight gain and inflammation are established factors that worsen insulin resistance, which then creates a harmful cycle that significantly elevates the risk for developing type 2 diabetes and other metabolic disorders.

As of 2021, an estimated 38.4 million Americans had diabetes, with approximately 90 to 95 per cent of them having type 2 diabetes, translating to about one in ten Americans. 

Infections

Chronic insomnia compromises immune function, elevating a person’s risk of contracting infections such as the common cold and influenza.

Sleep provides a critical period for the immune system to regulate itself, during which time the body produces essential proteins like cytokines and aids in the generation of immune cells.

Insufficient sleep can reduce the production and efficacy of key immune cells, including T-cells and white blood cells, which are necessary for identifying and eliminating harmful invaders. 

Sleep deprivation also disrupts the release of cytokines during the sleep-wake cycle, proteins that are vital for coordinating immune responses and managing inflammation.

A weakened defensive response and a potential increase in pro-inflammatory cytokines creates a state of chronic, low-grade inflammation that undermines the integrity of the immune system, mounting a less effective response to challenges. 

This can be seen in a reduced antibody production following vaccination and a prolonged recovery time from illness.