According to the National Institutes of Health, quality sleep is as essential for our survival as food and water. But how much sleep is optimum?
New research suggests that getting either too much sleep or too little sleep, particularly in mid- and later life, is associated with faster aging of almost all organ systems in the body.
The study, published in Nature, suggests that between 6.4 and 7.8 hours of sleep a night is associated with healthy aging, lower disease risk, and enhanced longevity. Any more or any less was associated with an increased risk of disease and mortality.
“The finding that around 6.4–7.8 hours of sleep appeared to be associated with healthier biological aging reinforces the idea that sleep is one of the most important modifiable lifestyle factors for long-term health. We often focus on supplements and advanced biohacking technologies, but sleep remains foundational for recovery, mitochondrial function and cellular repair.”
— Tunc Tiryaki, Founder of London Regenerative Institute Clinics, who was not involved in the study.
Using data from the UK Biobank on around half a million people, the researchers combined self-reported sleep durationwith biological aging clocks—measures of physiological rather than chronological age—for 23 organ systems.
From these, they identified organ-specific biological age gaps (BAGs), which can show differences between the biological and chronological age of these organs. BAGs have shown great predictive value for disease morbidity, cognition, and risk of mortality.
Previous research has shown a U-shaped relationship among sleep, brain aging, and mortality, and the researchers wanted to test, using BAGs, whether a similar relationship exists across multiple organ systems.
They also assessed whether long and short sleep duration were associated with increased all-cause mortality and systemic disease (not just in the brain) and late-life depression. And they examined whether sleep disturbances were modifiable risk factors for disease (or genetic predisposition), a result of disease, or a bidirectional relationship.
“What makes this study particularly interesting for longevity medicine is its systems-based approach. Instead of relying solely on chronological age, the researchers assessed biological aging using imaging, proteomics and metabolomics, providing a more comprehensive picture of aging across multiple organ systems.”
— Tunc Tiryaki
The researchers found that both short and long sleep were associated with brain and body health issues.
They found a significant association between short sleep, depressive episodes, and anxiety, as well as with obesity, type 2 diabetes, hypertension, ischemic heart disease, and heart arrhythmias (irregular heartbeat).
Both short and long sleep were linked to chronic obstructive pulmonary disease, asthma, gastritis, and gastroesophageal reflux.
The authors suggest that while short sleep appears to exert direct effects on multiple organ systems, long sleep appears to have greater neuropsychiatric effects and may reflect underlying latent disease.
Emer MacSweeney, MD, MBBS, MRCP, FRCR, CEO and Medical Director at Re:Cognition Health, who was also not involved in the study, explained some of the processes involved:
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“Too little sleep increases stress hormones, inflammation, and oxidative stress, all of which can accelerate aging in the brain and body. Sleep is also when the brain clears waste products through the glymphatic system, including proteins associated with neurodegenerative disease.”
— Emer MacSweeney
“On the other hand, excessively long sleep may reflect underlying health problems such as depression, inflammation, metabolic dysfunction, or early neurodegeneration. The brain appears to function best within a relatively stable sleep range rather than at either extreme,” MacSweeney told Medical News Today.
“Sleep optimization is one of the most effective forms of preventive health support,” Tiryaki said.
Although they found some genetic associations for short and long sleep duration, the researchers concluded that there were relatively few in their large sample, so they hypothesize that sleep duration is largely determined by environmental factors and is therefore modifiable.
So how can you help yourself get a good night’s sleep?
“Optimum sleep involves proper management of medical conditions, psychiatric conditions, and environmental stressors,” Sarathi Bhattacharyya, MD, pulmonologist, sleep medicine specialist, and medical director of MemorialCare Sleep Disorders Center at Long Beach Medical Center in Long Beach, CA, who was also not involved in the study, told MNT.
“Generally speaking, ensuring a consistent wake time to consistently align your circadian rhythm and practicing good ‘sleep hygiene’ in the evenings and a wind-down period before bed are key steps. Light exposure, late food or drink consumption, overly intensive exercise, and suboptimal treatment of medical/psychiatric conditions can all contribute to short sleep duration, either by delaying onset of sleep or by disrupting normal sleep progression,” he added.
However, he cautioned that it is important to avoid the urge to sleep in to compensate for a few nights of poor quality sleep “as these longer periods of sleep can actually disrupt your circadian rhythm and worsen the cycle of suboptimal sleep.”
“Sleep need is still individual. While this study identified an optimal range at a population level, genetics, age and health status all influence how much sleep a person needs. Sleep quality is also just as important as sleep duration.”
— Emer MacSweeney
The researchers used Mendelian randomization to minimize the possibility of reverse causality — that underlying illness was causing short and longer sleep duration, rather than sleep disturbance causing health problems.
However, Tiryaki cautioned:
“Although Mendelian randomization strengthens the argument against reverse causality, I suspect the relationship is at least partly bidirectional. Poor sleep may accelerate biological aging, while aging-related changes in metabolism, inflammation, and neurodegeneration can also impair sleep quality and duration. This is commonly observed in individuals with metabolic dysfunction or chronic inflammatory states.”
“Improving sleep quality and supporting circadian regularity may therefore contribute to greater resilience, recovery, and long-term healthspan,” he advised.
MacSweeney agreed:
“The authors themselves acknowledge they cannot completely exclude reverse causality. In neuroscience, we increasingly view sleep disruption as both a driver and an early marker of aging-related disease processes.”
