WS MoreOrLess: Sleeping: the 8-hour myth

Summary

More or Less: "Sleeping: the 8-hour Myth" (BBC World Service, Feb 21, 2015)

Episode Overview

This episode challenges the commonly held belief that eight hours of sleep is the universal ideal. Host Ruth Alexander explores recent research, debates the meaning of “optimal” sleep, and consults leading sleep specialists to dig into the science, statistics, and misunderstandings surrounding how much sleep is best for health and longevity.

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Key Discussion Points and Insights

Debunking the 8-Hour Sleep Myth

• Intro and Setup
  Ruth Alexander opens by questioning whether the classic advice of eight hours' sleep is as healthy as widely believed. She sets out to explore whether lying in for too long could actually be harmful.
  [00:19]

Sleep Duration and Mortality Risk: The Research

• Dr. Greg Jacobs (Sleep Disorders specialist, UMass Medical School)

  • For many years, eight hours was recommended, but newer studies suggest sleeping eight hours (or more) may actually pose a health risk.
    “…sleeping eight hours a night may be a health risk.” — Dr. Greg Jacobs [00:46]
  • He cites ~34 epidemiological studies (over 2 million people) showing a U-shaped relationship between sleep duration and mortality:

    “The lowest mortality is at the bottom of the U and that's seven hours of sleep... with long sleepers and short sleepers showing the greatest increase in mortality.” — Dr. Greg Jacobs [01:01]

• Explaining Mortality Risk
  Ruth clarifies that an “increased mortality risk” means a higher chance of dying sooner, not simply dying per se.
  [01:30]

Problems with Sleep Research: Self-Reporting and Accuracy

• Professor Franco Cappuccio (Cardiovascular Medicine & Epidemiology, Warwick)

  • Most studies rely on people's self-reported sleep hours, which is imprecise due to poor recall and confusion between time in bed vs. actual sleep.

    “It's very unusual to measure sleep very accurately… it has to be taken with a pinch of salt.” — Prof. Franco Cappuccio [02:03], [02:16]

  • Most in the US and UK report 6–8 hours of sleep, which seems “safe,” but risks increase outside this range.

    “More or less than that… does appear to carry a risk of developing conditions like high blood pressure, diabetes and cardiovascular disease…” — Ruth Alexander [02:35]

  • Data:

    • 12% more short sleepers had died vs. 6–8 hour sleepers
    • 30% more long sleepers had died vs. the same baseline
      [03:21]

Is Too Much Sleep Really to Blame?

• Short Sleep = Clear Risks

  • Evidence: Sleep deprivation causes measurable adverse effects on blood pressure, glucose metabolism, and increases disease risk.

    “There is a wealth of evidence… that if you don't sleep enough, we say six hours or more, you are likely to develop alterations… and you are at greater risk.” — Prof. Franco Cappuccio [03:58]

• Lifestyle, Stress, and Underlying Illness

  • Professor Jim Horne (UK Sleep Expert)

    • Points out sleep deprivation studies often involve extreme conditions, potentially muddying conclusions.

      “Is your life so stressful?… It's not necessarily the short sleep... the problem is the fact that you are maybe having a stressed lifestyle.” — Prof. Jim Horne [04:47]

    • Increasing sleep may not offset the risks if lifestyle factors are at play.

  • Sleep as a Symptom, Not a Cause (for Long Sleepers)

    • Both Horne and Cappuccio agree: Longer sleep duration is linked to ill health, but is likely a symptom of underlying issues rather than a direct cause.

      “Long sleep is a symptom of a more serious condition… what we could not adjust for was for some pre existing, pre symptomatic ill health.” — Prof. Franco Cappuccio [05:39]

New Research and Emerging Theories

• Professor Sean Youngstedt (Arizona State University)

  • Few studies examine long sleepers due to pharmaceutical interests favoring short sleep research.
  • His study: Young adults added ~2 hours to their night for three weeks—resulting in increased depression, inflammation, soreness, and back pain.

    “They had increases in depressed mood and they had increases in inflammation.” — Prof. Sean Youngstedt [06:53]

  • Suggests “prolonged inactivity” could be problematic.
  • Ongoing experiments are investigating if cutting time in bed for long sleepers improves health/outcomes.

• Consensus on Sleep Quality

  • All experts agree: Sleep quality might matter even more than duration, but it's even harder to quantify.
    [07:11]

So, What’s the Ideal Amount of Sleep?

• Dr. Greg Jacobs
  • National Sleep Foundation data: Median adult sleep duration is consistently 7 hours (US and globally).

    “There is something about seven hours of sleep that seems to be the ideal number… lowest mortality risk.” — Dr. Greg Jacobs [07:56]

Final Perspective: Personal Variability

• Ruth Alexander
  • If you feel fine sleeping more, don’t panic—there’s no conclusive evidence a long lie-in is dangerous if you’re healthy.

    “There's no sure evidence that the lie-in is going to kill you.” — Ruth Alexander [08:49]

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Memorable Quotes

• “Sleeping eight hours a night may be a health risk.”
  — Dr. Greg Jacobs [00:46]

• “The lowest mortality is at the bottom of the U and that's seven hours of sleep.”
  — Dr. Greg Jacobs [01:01]

• “It's very unusual to measure sleep very accurately… it has to be taken with a pinch of salt.”
  — Prof. Franco Cappuccio [02:03], [02:16]

• “Long sleep is a symptom of a more serious condition.”
  — Prof. Franco Cappuccio [05:39]

• “They had increases in depressed mood and they had increases in inflammation.”
  — Prof. Sean Youngstedt [06:53]

• “There is something about seven hours of sleep that seems to be the ideal number… lowest mortality risk.”
  — Dr. Greg Jacobs [07:56]

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Timestamps for Key Segments

• 00:19 – Introduction and framing the "8-hour myth"
• 00:46 – Dr. Jacobs challenges 8-hour rule, describes U-shaped mortality curve
• 02:03 – Prof. Cappuccio on methodology: problems with self-report data
• 03:21 – Quantifying risk: 12% (short sleepers), 30% (long sleepers) higher mortality
• 03:58 – Short sleep: experimental evidence of health risks
• 04:47 – Prof. Horne: Sleep deprivation studies and stressed lifestyles
• 05:39 – Long sleep likely a marker of hidden illness, not a cause
• 06:53 – Prof. Youngstedt’s study: mood and inflammatory drawbacks of oversleeping
• 07:56 – Dr. Jacobs: Seven hours is consistently the “ideal” in studies
• 08:49 – Ruth Alexander’s conclusion: individual variation matters

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Summary Takeaways

• The "eight-hour rule" is outdated; data suggest seven hours is closer to the “sweet spot” for most adults.
• Both short and very long sleep are associated with higher health risks—but causality is complex, especially for long sleep, which likely reflects hidden illnesses.
• Self-reported sleep research is fraught with inaccuracies, so recommendations should be nuanced.
• Don’t stress over exact numbers: If your sleep duration leaves you feeling well, there’s little evidence a long lie-in alone is harmful.
• Sleep quality likely matters as much as (or more than) quantity.

For more information and episodes, visit BBC.com/moreorless.

Transcript

[Ruth Alexander]

This is the short edition of More or Less, first broadcast on the BBC World Service.

[BBC Announcer]

Thank you for downloading from the BBC. For details of our complete range of podcasts and our terms of use, go to bbcworldservice.com podcasts

[Ruth Alexander]

hello and welcome to More or Less on the BBC World Service. I'm Ruth Alexander. This week, could having long lie ins kill you? I try, although often fail, to get eight hours sleep, which I always thought was the ideal.

[Dr. Greg Jacobs]

That is not true until I heard

[Ruth Alexander]

from Dr. Greg Jacobs, a specialist at the Sleep Disorders center at the University of Massachusetts Medical School in the us

[Dr. Greg Jacobs]

we were given that recommendation for many years and now the research over the past 10 years suggests that sleeping eight hours a night may be a health risk.

[Ruth Alexander]

So Greg believes that getting eight hours sleep a night might actually be bad for you.

[Dr. Greg Jacobs]

There have been about 34 studies. These are epidemiologic studies that follow people over time, involving over 2 million people that consistently show that there's a U shaped relationship between sleep duration and mortality. The lowest mortality is at the bottom of the U and that's seven hours of sleep. And then as you sleep less than seven or more than seven, there's a gradual increase in mortality risk, with long sleepers and short sleepers showing the greatest increase in mortality.

[Ruth Alexander]

Of course we're all going to die one day. So what's meant by increased mortality risk? Well, it means you've got more chance of dying sooner rather than later. More on that shortly. But first let's find out more about how our sleep habits are studied. Although some studies have shown that eight hours sleep is associated with health problems, we probably shouldn't talk about eight hours so precisely. In the view of Franco Cappuccio, a professor of cardiovascular medicine and epidemiology at the University of Warwick in the uk. He's done a detailed analysis of sleep studies.

[Professor Franco Cappuccio]

It's very unusual to measure sleep very accurately. We tend to rely on very simple methods of asking people on average how many hours they sleep a night. It has to be taken with a

[Ruth Alexander]

pinch of salt because people aren't very good at accurately reporting how long they're sleeping for naturally.

[Professor Franco Cappuccio]

Obviously you have to rely on your memory or your recollection and the fact that you don't know whether you're reporting time in bed or time asleep and whether you are accounting for naps and so forth, lots of approximations.

[Ruth Alexander]

So relying on people's self reports makes this an uncertain science. And apparently we have a tendency to overestimate how long we've been Asleep. But if you think you sleep between six and eight hours a night on average, like three quarters of people say they do in countries like the US and the uk, you've got nothing to worry about, he says. More or less than that, though, does appear to carry a risk of developing conditions like high blood pressure, diabetes and cardiovascular disease or, or worse, as you

[Professor Franco Cappuccio]

sleep more than eight hours, so 9, 10, 11, or less than six, so 5, 4, 3, you have a very sharp rise in what we estimate to be the risk of developing these conditions or to die early later on in life.

[Ruth Alexander]

How big is this risk? When the researchers went back to the people they'd surveyed, they found that 12% more short sleepers had died compared to the six to eight hour sleepers. And when the researchers went back to the long sleepers in, even more of them had died, 30% more compared to the number of six to eight hour sleepers. So it seems at first sight that too much sleep is worse for you than too little sleep. But that's not what's going on. Franco Cappuccio says short sleep is bad for you. That's pretty clear, he says, pointing to other studies which have shown that if you deprive people of sleep, it does cause a bad physical reaction.

[Professor Franco Cappuccio]

You may, for instance, increase their blood pressure, you may increase their ability to develop diabetes, basically by impairing your ability to utilise glucose. So there is a wealth of evidence experimentally to back up the idea that if you don't sleep enough, we say six hours or more, you are likely to develop alterations of your metabolism and your functions, which if sustained over your lifetime, over many years, you are at greater risk of a number of things.

[Ruth Alexander]

But another sleep specialist in the uk, Professor Jim Horn, argues that sleep deprivation experiments have been too extreme, put people under too much stress for the results to be reliable. He's a sleep expert, but says we should think more about what's going on in our waking hours.

[Professor Jim Horne]

The evidence of people who are very short sleep. People sleep only five hours a night. Then one has to ask the question, this is very low and why are you only sleeping five hours a night? Is your life so stressful? Are you spending too much and agitated wakefulness? And clearly it's not so much lack of sleep, which the problem is the fact that you are maybe having a stressed lifestyle and that might be the factor which is causing maybe cardiovascular disease, for example. So it's not necessarily the short sleep. And there's no real evidence that increasing the sleep of these people will actually offset the likelihood of that disease getting worse.

[Ruth Alexander]

Although Franco Cappuccio says things like stress are taken account of when analysing experiment results. But what about the apparently even larger ill effects of long sleep? This is where Jim Horn and Franco Cappuccio agree. They say although sleeping for a long time is linked to ill health, there's no evidence that it's causing the ill health.

[Professor Franco Cappuccio]

Nothing at all. On the other hand, we know very well long sleep is a symptom of a more serious condition. And although in our studies we try and allow for all the possible reasons that may confound our association, depression, we try to allow for that the use of sleeping pills or hypnotics and even adjusting for all these factors, the association was still there. But we still believe that what we could not adjust for was for some pre existing, pre symptomatic ill health that people in the long sleeping range would have that we couldn't pick up.

[Ruth Alexander]

So the increased risk of health problems that you see in people who sleep for a long time is probably not the sleep causing that. The sleep itself is probably a marker for some underlying condition that the person may not know yet that they have. Indeed, but not everyone agrees. Sean Youngstedt, professor at Arizona State University in the us says short sleep has been studied a lot because that's what pharmaceutical companies, sleeping tablet manufacturers are interested in. He's one of the few people researching long sleep and says he's getting interesting results.

[Professor Sean Youngstedt]

We did a study in young adults, only 14 people, where we asked them to spend three hours more in bed a night for three weeks. They were only able to spend two hours more in bed and they had increases in depressed mood and they had increases in inflammation.

[Ruth Alexander]

As well as the inflammation and depression, the teenagers also complained about soreness and back pain, supporting a theory put forward by Kevin Morgan at Loughborough University in the uk. Sean wonders whether the problem with long sleep is prolonged inactivity. He's carrying out an experiment where long sleeping and average sleeping adults are asked to spend an hour less in bed. Maybe reducing time spent in bed might also consolidate sleep. He posits it helps insomniacs. Sleep quality is something all the scientists agree could affect your health. The problem is it's even harder to measure than how long you sleep. So how much sleep should you be getting? Well, despite the caveats that people are very unreliable witnesses to their own sleep, Greg Jacobs thinks we do have an idea.

[Dr. Greg Jacobs]

Every spring in the United States, the National Sleep foundation polls several thousand adults in a random scientific sampling and they find something very interesting. That the typical adult today reports seven hours of sleep, and that actually seems to be the median sleep duration in the adult population around the world. That suggests there's something about seven hours of sleep that is kind of natural for the brain. And secondly, they find that the majority of adults still report that they feel rested and energetic, and only about 5% feel sleepy on a daily basis. There is something about seven hours of sleep that seems to be the ideal number in terms of what people naturally get and what we see in terms of ideal health outcomes in terms of lowest mortality risk. So seven hours of sleep keeps turning up over and over again.

[Ruth Alexander]

But if you enjoy sleeping, spend a lot of time in bed and feel perfectly well, you're probably just fine. There's no sure evidence that the lion is going to kill you. Our email address is more or lessbc.co.uk you can get a download of this program and previous editions at our website, BBC.commoreorless.

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