Is lack of sleep linked to higher mortality?
Is lack of sleep linked to higher mortality?
Hello everyone,
According to a 2022 sleep study, 71% of adults living in the UK do not get the recommended 9 hours sleep a night, and 14% of those do not even sleep 5 hours a night!
This problem is not UK specific – 62% of adults around the world say they don’t sleep as well as they would like to. We know that if we don’t get a good night’s sleep, we feel tired the next day and may find it harder to focus, but could a lack of sleep also be affecting our health? We asked 10 experts in sleep research, gastroenterology and epidemiology, ‘Is lack of sleep linked to higher mortality?’, here is what they said…
EXPERT CONSENSUS
Is lack of sleep linked to higher mortality?
10 out of 10 experts say ‘yes’
What is the evidence connecting sleep and mortality?
Dr Tetyana Kendzerska, an expert in sleep research from Ottawa University in Canada, says “Despite some inconsistencies in the published literature, the accumulated evidence suggests an increased risk of all-cause mortality associated with self-reported short sleep duration (usually defined as ≤ six h/night), among both males and females, compared to individuals who report, on average, a ‘medium’ amount of sleep per night (generally defined as 7 to 8 h/night) (systematic review and meta-analyses: Gallicchio et al., 2009; Cappuccio et al., 2010; Alves da Silva et al., 2016; Yin et al., 2017).”
Dr Taha Qazi, an expert in gastroenterology from the Cleveland Clinic in the USA, says “Lack of sleep or poor sleep is likely associated with a higher mortality. Namely poor sleep has been linked with an increased incidence and progression of CVD [cardiovascular disease], diabetes, obesity, cancer and premature mortality.”
Extreme lack of sleep shows an even stronger link to mortality. Professor Zahra Moussavi, an expert in sleep research from Manitoba University in Canada, says “Studies on mice have shown that complete sleep deprivation kills them within a week or two.”
Why is connecting sleep and mortality complicated?
Dr Jason Wong, an expert in epidemiology from the National Cancer Institute in the USA, says “Mortality is a complicated outcome and there are many forms of mortality related to hundreds of different cancers, cardiovascular disease, deaths of despair, metabolic disease, accidents etc. Each of these forms of mortality depend on incidence or occurrence of that certain disease.” Essentially, ‘mortality’ is a very broad outcome that could have many different causes (such as diseases or accidents), so it is difficult to connect it to particular characteristics such as sleep.
The other complication is that a ‘link’ between sleep and mortality could be correlation rather than causation (i.e. if you suffer from a certain condition that increases mortality, this condition may also affect your ability to sleep. This doesn’t mean that your lack of sleep is causing increased mortality). This is emphasised by Dr Dennis Auckley, an expert in sleep research from Case Western Reserve University in the USA, who says the studies described above “do not, and cannot, establish a cause and effect relationship, but show an association.”
Dr Kendzerska expands, saying “Some but not all of the excess mortality among the short sleepers may be due to differences in the characteristics of the individuals who comprise this group; for example, individuals who report shorter sleep time are more likely to be in low income and poorer overall health and to have been diagnosed with medical conditions, including depression, than individuals who report average sleep times.”
How can sleep affect mortality?
Is there a biologically plausible way in which sleep could cause increased mortality? Dr Auckley says “there are plausible biologic and physiologic mechanisms by which this may be a cause and effect relationship (chronic lack of sleep leading to higher mortality). Growing data in well controlled trials have found that sleep deprivation leads to pathophysiologic changes that result in worsening metabolic and cardiovascular outcomes (i.e. diabetes risk, weight gain, hypertension) that could be mediators for higher mortality rates.”
Dr Kenderska says “The specific mechanisms underlying the association between short sleep duration and all-cause mortality are unclear. Potential mechanisms suggested are adverse endocrinologic, immunologic, and metabolic effects associated with short sleep as well as chronic inflammation.”
The takeaway:
Lack of sleep is linked to higher mortality rates, but whether this relationship is causative is not completely clear.
May the facts be with you!
Eva
Why do we need sleep?
Learn more about sleep with our deep-diving reviews (Part 1 and Part 2).
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