2 thoughts on “How Much Sleep Do You Really Need?

  • March 25, 2010 at 6:12 am

    Correlation does not necessarily equal causation. Where is the evidence that higher mortality is CAUSED by shorter or longer sleep periods than are experienced by those individuals who fall into the lower mortality zones?

    Also, some of the (implied) conclusions of example studies cited are questionable without any information on the study design, methodology, sample selection, factoring of other variables, etc. For example, Kripke cited a study that correlated over 69% of motor vehicle accidents with drivers who sleep 7-8 hours. Does this correlation actually mean that drivers who sleep 7-8 hours are much more likely to be involved in vehicular crashes because of their sleep durations, or were an overwhelmingly vast majority of study participants individuals who sleep 7-8 hours of sleep? What other variables were accounted for that might have influenced the study results? Again, I saw no mention of causation, just correlation.

    I respect my body/mind’s wisdom to control my circadian cycle which has not substantially changed in the 30+ years since young adulthood (and I rarely have the need to use an alarm clock). As such, I will continue enjoy my 8-9 hours of sleep per night worry-free that I sleep too much or that I might die sooner than those who sleep hours than me. And if my sleep patterns significantly change for no apparent reason, I will be sure to visit my primary care physician to rule out any underlying medical condition that might actually CAUSE my eventual mortality.

    Not a particularly enlightening lecture in my opinion.

  • March 25, 2010 at 3:35 pm

    Kripke repeatedly stressed throughout the talk and the Q&A that the studies were correlative, not causative, and that controlled trials are needed.


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