Skipping just one night of sleep causes healthy adults to see a spike in immune cells linked to chronic inflammation, a key feature of obesity, according to new research. The good news is that once normal sleep is restored, things return to normal, highlighting the powerful link between sleep and immune health.
Scientists have long investigated the link between sleep and weight. Over the years, it has become apparent that sleep regulation is not solely about the brain but depends on a complex interaction between the brain and the rest of the body. While the impact of sleep deprivation on health is known, the mechanism underlying this association is less understood.
In new research, the Dasman Diabetes Institute (DDI) in Kuwait examined the impact of even a short period of sleep deprivation on a healthy person’s immune system and how this might impact their risk of developing conditions like obesity, diabetes, and heart disease.
“Our findings underscore a growing public health challenge,” said the study’s lead and corresponding author, Dr Fatema Al-Rashed, a researcher from DDI’s Immunology and Microbiology Department. “Advancements in technology, prolonged screen time, and shifting societal norms are increasingly disruptive to regular sleeping hours. This disruption in sleep has profound implications for immune health and overall well-being.”
The researchers recruited 237 healthy adults with self-reported normal liver, heart, lung, and kidney functions. People with doctor-diagnosed diabetes, obstructive sleep apnea (OSA), high blood pressure or those on medications for high blood pressure were excluded. As were those with a history of significant heart problems (heart attack, coronary artery bypass graft (CABG) surgery, coronary angioplasty or ‘stents’) and/or a family history of premature (before age 40) death from cardiac causes. Additionally, people with diagnosed depression or taking medications known to affect sleep quality or body weight by altering metabolism were excluded.
Participants were divided into three groups – lean, overweight, and obese – based on their body mass index (BMI). The obese cohort was further stratified into individuals with low-, moderate-, and high-risk obesity. To track activity and sleep, participants wore an accelerometer positioned over the hip for seven consecutive days, except when bathing. For participants to remain in the study the accelerator had to be worn for at least four nights, which previous research has found necessary for determining accurate sleep-wake patterns. Blood samples were taken to measure cytokines and chemokines, signaling proteins that help regulate inflammation and immune activity, and monocytes, white blood cells that help fight infection and heal damage.
The researchers found that, compared to the lean participants, obese individuals had significantly lower sleep quality and higher chronic low-grade inflammation. Overweight and obese participants also had significantly higher numbers of non-classical monocytes (NCM), a subclass of monocytes that act as immune surveillance cells, and elevated levels of proinflammatory cytokines.
The researchers then conducted a control experiment to “probe the interplay between sleep deprivation and immune cell dynamics.” They subjected five ‘normal-weight’ individuals – two males and three females – to sleep deprivation for 24 hours. They observed an acute, significant uptick in circulating NCM levels that reverted to baseline a couple of days later when normal sleep was restored.
“This is an interesting study,” said Professor Si Ming Man, an immunologist at The John Curtin School of Medical Research in Australia who wasn't involved in the study. “The findings showing that poor-quality sleep increases low-grade inflammation are sound.
“What is also interesting to me is that the increased inflammation is reversible with good sleep, which has significant health implications because it means we can catch up on our ‘lost’ sleep during the week to make sure we are not in this vicious cycle of persistent and chronic inflammation that will make us more likely to get things like type 2 diabetes and cancer down the line.”
The researchers said that further research will continue to explore the mechanisms linking sleep deprivation, monocytes, and inflammation in obesity. Additionally, they plan to evaluate interventions designed to improve sleep quality in obese individuals for their ability to dampen the body’s immune response and reduce inflammation.
“In the long term, we aim for this research to drive policies and strategies that recognize the critical role of sleep in public health,” Al-Rashed said. “We envision workplace reforms and educational campaigns promoting better sleep practices, particularly for populations at risk of sleep deprivation due to technological and occupational demands. Ultimately, this could help mitigate the burden of inflammatory diseases like obesity, diabetes, and cardiovascular diseases.”
The study was published in The Journal of Immunology.