For generations, the advice has been clear: get a full 8 hours of shut-eye every night if you want to stay healthy and keep the wrinkles at bay.
Cutting your rest short is always framed as a surefire way to fast-track the ageing process. However, fresh research completely challenges this traditional wisdom, suggesting that the ideal amount of rest to keep your body young is actually lower than we think. Tracking the biological age of internal organs reveals that getting a bit less sleep actually fits the optimal zone for longevity.
Before you force yourself to stay in bed for an extra hour tomorrow morning, you might want to hear this data because hitting that traditional target might actually be doing your body more harm than good.
Scientists dug deep to uncover sleep’s impact on ageing.
Researchers examined sleep data from around 500,000 people taking part in the UK Biobank, a long-running health project in Britain. They compared participants’ reported sleep habits with measurements of biological ageing across multiple parts of the body, including the brain, lungs, liver, immune system, and skin.
The findings were published in the journal Nature and pointed to a surprisingly narrow window of sleep that appeared to be linked to slower biological ageing. Rather than the widely cited eight hours, the sweet spot turned out to be considerably shorter.
The sleep range linked to slower ageing is one many people naturally fall into.
People sleeping between 6.4 and 7.8 hours a night appeared to age more slowly than those getting much more or less. This pattern showed up consistently across multiple organs and body systems, making it one of the more comprehensive studies of its kind.
The researchers also spotted a slight difference between men and women. Women appeared to fare slightly better with around 6.48 hours of sleep on average, while men fared best at around 6.42 hours. The gap is small but lines up with previous research suggesting women may need marginally more sleep than men overall.
Sleeping too little can cause serious problems.
Getting fewer than six hours a night was strongly associated with a higher risk of several health problems in the study. These included heart failure, type 2 diabetes, anxiety, and depression, suggesting that consistently short sleep is far from harmless even if eight hours isn’t necessarily the target.
This part of the findings isn’t particularly new, since the risks of poor sleep have been well documented for years. What the study adds is the context of where too little sleep sits within a broader picture that includes the risks of sleeping too much as well.
The risks of sleeping too much can’t be overstated, either.
Perhaps the most surprising part of the research is that sleeping significantly more than eight hours was associated with its own set of health concerns. Researchers found links between longer sleep durations and conditions including major depressive disorder, bipolar disorder, ADHD, and alcohol dependency.
This doesn’t mean that sleeping more causes these conditions, and it’s worth noting that some of them can themselves affect sleep patterns. But the findings do suggest that treating sleep as something where more is always better isn’t quite right, and that there may genuinely be such a thing as too much.
The findings aren’t the full picture, of course.
The research has some limitations worth bearing in mind before anyone starts adjusting their alarm with scientific precision. Participants reported their own sleep habits through questionnaires, which means some may have over or underestimated how much they were actually getting.
Sleep needs also vary considerably from person to person, depending on age, existing health conditions, and individual biology. The figures from this study represent statistical patterns across a very large group, rather than a universal prescription that applies equally to every individual.
Consistency might matter more than the number.
A separate study published in the journal Sleep found that keeping consistent sleep and waking times was actually a stronger predictor of overall mortality risk than the total number of hours spent in bed. In other words, going to bed and waking up at roughly the same time each day may matter as much as hitting any particular duration.
This suggests that while many people focus on chasing a specific number of hours, the bigger challenge might simply be maintaining a reliable routine. The body’s internal clock responds well to regularity, and disrupting it consistently, even in the name of getting more sleep, may come with its own costs.
