An Australian study published in PLOS Medicine found that sleeping more than 9 hours a day could increase your risk of mortality. To this statement, there are many caveats.
Over 200,000 Australians aged 45 years or older participated in this 6-year study. Participants were up to 5 times more likely to die if they were physically inactive (< 150 minutes per week), sedentary (> 7 hours per day), had long sleep durations (> 9 hours per day), smoked and had high alcohol intake.
However, all information was self-reported and the researchers lacked long-term lifestyle data.
Participants were asked “How long did you sleep?” to which they probably responded the number of hours for which they were in bed. Unfortunately, this says nothing about sleep quality. In fact, higher numbers may translate to fragmented sleep due to stress or illness.
Additionally, let’s consider an alternative theory. Many people talk about “having a reason to get up in the morning” and “the will to live”. Yet if someone is spending all day in bed, perhaps there’s an underlying cause for that behaviour, such as mental illness or iron deficiency.
Nevertheless, the study does – unnecessarily – reinforce the importance of living a healthy lifestyle, but I don’t think worrying about sleeping in should be on anyone’s radar.
For more, see how the media spun the study: