It’s all about the right duration: Sleeping at night that’s too short or too long can cause long-term damage to our health – and also causes our organs to age prematurely, as researchers have found. The biological “clocks” of nine different organ systems, including the liver, lungs, heart and brain, age faster if we sleep less than six hours or more than eight hours per night for a long time. On the other hand, between 6.4 and 7.8 hours of sleep is optimal, reports the team in “Nature”.
Sleep is essential for us: Our brain needs the rest to flush out waste, recalibrate synapses and store what we have learned, muscles and organs need this phase to regenerate. If we consistently don’t sleep enough or our nighttime sleep is repeatedly disturbed, our physical and mental health suffers. Studies show that sleeping less than five hours increases the long-term risk of depression, cardiovascular disease, diabetes and obesity.
17 organ systems and 23 different age clocks
But sleeping too long or too short also affects our organs and causes them to age prematurely, as an international research team led by Junhao Wen from Columbia University in New York has discovered. “Previous studies have shown that sleep is closely linked to aging and disease burden in the brain,” explains Wen. He and his team have now, for the first time, comprehensively investigated whether and in what form this also applies to individual organs in the rest of our body.
For their study, Wen and his team used the medical data of around half a million participants in the UK Biobank’s long-term study. They evaluated the average sleep duration of the test subjects and determined the biological age based on blood values and organ-specific proteins as well as MRI images for 17 different organ systems. The team used several different “age clocks”. “For the liver, for example, there is an age clock based on proteins, one for metabolic data and one based on imaging,” explains Wen. “This allows us to see more precisely how sleep duration influences these functions.”
Sleep effects show U-shaped curve
The evaluation showed a striking U-shaped curve: If study participants consistently slept for less than six hours or longer than eight hours, this had negative effects on almost all organs. Systems such as the lungs, liver, heart, digestive tract, skin or kidneys, but also the immune system, hormonal balance and metabolism had aged prematurely in these test subjects. “Our study shows that too little or too much sleep causes almost every organ to age faster,” reports Wen.
This has consequences: “Whether it is too short or too long – a disturbed sleep pattern is closely linked to a wide range of systemic diseases and an increased risk of death,” write the researchers. Lack of sleep often has a direct effect on the organ systems. What is particularly harmful is increased physiological stress and a dysregulation of natural rhythms. On the other hand, sleeping too long at night primarily has consequences for the brain and then indirectly leads to long-term physical consequences via neuropsychiatric effects, as the analyzes showed.
How much sleep is optimal?
According to Wen and his team, this underlines how important the right amount of sleep is for our health. “The results once again show that sleep has far-reaching molecular and physiological influences on the entire body,” said the team. This is particularly important because night sleep is a factor that we can influence ourselves. If you want to keep your organs and brain as young as possible, you should sleep between 6.4 and 7.8 hours at night.
Source: Junhao Wen (Columbia University, New York) et al., Nature, 2026; doi: 10.1038/s41586-026-10524-5