Sleeping too much or too little? It can quietly shorten your life

A Korean study finds both irregular and prolonged sleep raise death risk, with 7-8 hours of consistent rest emerging as the healthiest pattern

We’ve all heard the advice to get a 'good night’s sleep', but what does that really mean? A new research from Korea suggests it’s not just the number of hours that matter, but also how consistent your sleep patterns are.

 

The study, titled 'The impact of sleep health on cardiovascular and all-cause mortality in the general population', was published in the journals of Scientific Reports. It says that while 7–8 hours of steady rest offers the best protection, sleeping too long and keeping irregular hours is linked to higher mortality risk.

 

How the study was conducted

 

The research, conducted by the Korea Disease Control and Prevention Agency, tracked over 9,600 adults aged 40–69 years for more than 15 years. Participants reported their sleep duration and regularity, which were grouped as:

 

 

• Less than 7 hours
• 7–8 hours (the reference, or healthiest group)
• More than 8 hours

 

The study also examined whether people slept and woke up at consistent times and analysed differences between men and women, as well as across age groups.

 

What the study found

 

• Prolonged sleep duration (> 8 hours) was independently associated with an increased risk of all-cause mortality.
• Prolonged sleep duration (> 8 hours) with regular sleep, and irregular sleep patterns combined with short sleep duration (< 7 hours) were both independently associated with an increased risk of all-cause mortality compared to the reference group (7–8 hours with regular sleep).
• In sex-specific analyses, women with long and irregular sleep patterns and men with either long and regular or short and irregular sleep showed a significantly increased risk of all-cause mortality.
• In age-specific analyses, short sleep duration was generally associated with increased risk in participants aged 40–49 years, whereas prolonged sleep duration was associated with worse outcomes in those aged over 60 years.

 

Why longer sleep isn’t better

 

It may sound counterintuitive, but experts say sleeping for long stretches doesn’t mean your body is getting more rest. Instead, it could point to hidden health issues or poor-quality sleep. People who don’t get enough sleep during the week may try to 'catch up' by sleeping longer, but this often signals lower sleep efficiency. Over time, this pattern has been tied to health risks such as diabetes, obesity, and high blood pressure.

 

Short and irregular sleep patterns can trigger biological stress. They affect how your body regulates blood sugar, raise stress hormone levels, and put pressure on the heart and blood vessels. Women may face added disruptions from hormonal shifts, stress, or caregiving responsibilities, while men are often impacted by conditions like sleep apnoea or long working hours.

 

How to 'sleep right'

 

This study reinforces something simple but powerful: good sleep isn’t just about the hours—it’s about regularity. Adults who consistently sleep 7–8 hours a night appear to lower their long-term health risks.

 

Tailoring sleep habits according to age and sex is likely to enhance health outcomes, highlighting the value of personalised sleep health strategies moving forward.

   

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