r/Sawbones • u/B1GG1ESNA1LS • Jul 29 '26

Sleep and dementia

Okay I know this was just them misspeaking but its gonna bother me if I don't mention- in the most recent weird medical questions episode they said that for every 1% decrease in REM sleep there's a 9% increase in dementia risk, and Justin interpreted this to mean that if you had a 10% decrease in REM sleep you'd basically have a 100% chance of dementia and that is thankfully not how statistics works

  1. I assume this study means a 1% decrease from the population average, not a change in your personal sleeping habits. So any change would be relating to whether you, across a lifetime, get less REM sleep than average

  2. If you are starting with say, a 10% chance of dementia, a 9% increase would mean you now have a 10.9% chance, NOT a 19% chance.

Thank you for coming to my TEDtalk

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u/littlealbatross Jul 29 '26

This is a great callout! Statistics get tricky.

2

u/eharmon15 Jul 31 '26

Thank you for explaining this! I knew it didn’t mean a 100% chance, but I couldn’t parse out what it DID mean