A recent study by Columbia University Irving Medical Center analysing biological clocks across the human body suggests that both — too little sleep and excessive sleep may accelerate ageing in multiple organs, including the brain, heart, lungs, and immune system.
“Previous studies have found that sleep is largely linked to aging and the pathological burden of the brain. Our study goes further and shows that too little and too much sleep are associated with faster aging in nearly every organ, supporting the idea that sleep is important in maintaining organ health within a coordinated brain-body network, including metabolic balance, and a healthy immune system,” says study leader Junhao Wen, assistant professor of radiology at Columbia University Vagelos College of Physicians and Surgeons.
According to the study, in the UK Biobank population, “both short sleep (fewer than 6 hours) and long sleep (greater than 8 hours) were associated with faster aging, while the least amount of aging occurred in people who reported between 6.4 and 7.8 hours of sleep per day.” It, however, clarified that this “does not mean that sleep duration alone causes organs to age faster or slower, but it suggests that both insufficient and excessive sleep may be markers of poorer overall health across the body.”
Does this imply that ageing is largely linked to sleep patterns? According to Dr Manas Mengar, sleep is far more than simple rest; it is one of the body’s most important repair mechanisms.
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Dr Mengar explains that during healthy sleep, the brain clears metabolic waste, hormones rebalance, the immune system resets, and organs such as the lungs and heart recover from daily stress. All of this directly affects the body’s biological clock, or the speed at which the body ages internally.
“When sleep drops below six hours, the body stays in a prolonged stress state,” he says. “Inflammation rises, blood pressure increases, breathing quality worsens, and immune recovery becomes weaker.” He, however, cautioned that excessive sleep can also signal underlying problems.
“Sleeping excessively may reflect poor-quality sleep, fragmented sleep, low oxygen levels
In clinical practice, oversleeping is often more of a red flag than a direct cause,” says Dr Mengar. He explains that many people who sleep for nine or 10 hours still wake up exhausted because the quality of sleep remains poor. Conditions such as obstructive sleep apnea, obesity, thyroid disorders, chronic lung disease, depression, or low-grade inflammation can increase the body’s demand for sleep. “In sleep apnea especially, breathing repeatedly stops during sleep, reducing oxygen supply and preventing deep restorative sleep,” says Dr Mengar. “Patients may think they are sleeping enough, but biologically the body remains exhausted.”
He adds that excessive sleep should not simply be dismissed as laziness. “Sometimes it is the body’s way of signalling that something deeper needs attention.”
“Many younger adults compensate for poor sleep with caffeine, exercise, or routine, so outwardly they appear fine,” says Dr Mengar. “But internally, chronic sleep disruption can quietly affect metabolism, hormone regulation, lung recovery, immunity, and mental health long before symptoms become obvious.”
According to him, doctors are increasingly seeing younger patients experiencing fatigue, anxiety, poor concentration, elevated blood pressure, weight gain, and early insulin resistance linked to years of erratic sleep schedules.
“The body can tolerate occasional sleep loss,” he says. “But chronic disruption gradually builds biological stress.” Dr Mengar notes that sleep is no longer being viewed as a lifestyle luxury but as a core pillar of preventive medicine.
The biggest concern today is that poor sleep is no longer an isolated problem — it is feeding into almost every major chronic disease, says Dr Mengar.
He points to stronger links between chronic sleep imbalance and conditions such as hypertension, diabetes, obesity, depression, heart rhythm disorders, weakened immunity, and worsening respiratory diseases.
According to Dr Mengar, healthy sleep in 2026 is not simply about spending eight hours in bed.
“It means consistent, uninterrupted, restorative sleep with regular timing,” he explains. “For most adults, the sweet spot remains roughly seven to eight hours nightly.”
He also stresses the importance of sleep hygiene habits, including limiting late-night screen exposure, maintaining fixed sleep schedules, reducing alcohol intake before bedtime, and seeking
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