I heard that sleeping long hours can damage brain functions and harm the heart. Is that true?

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    To the downvoter: I was about to downvote this "silly question" too until I googled it.
    – Carey Gregory
    Commented Apr 1, 2016 at 0:58
  • here you go. Interesting article: Extended Wakefulness jneurosci.org/content/34/12/4418.short and this one Insufficient Sleep cdc.gov/features/dssleep
    – bantandor
    Commented Apr 1, 2016 at 8:43
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    @bantandor that's for sleeping too little. The OP is asking about sleeping too much.
    – YviDe
    Commented Apr 1, 2016 at 11:35
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    Welcome to health SE :-) It's an interesting question, but your own research or at least giving a rough number of hours that you consider "too much sleep" would help a lot. Thanks!
    – Lucky
    Commented Apr 1, 2016 at 12:10
  • 2
    Does this answer your question? How much sleep is too much? Commented Sep 16, 2020 at 9:47

1 Answer 1


Although this question is hard to research - you're dependent on self-reported data on sleeping hours, and there are many confounders that influence this relation (why do people sleep longer? maybe people who sleep longer are more likely to be without a job, and being without a job is also associated with higher risk of heart disease etc.).

However, the consensus seems to be that: Yes, it has been found that longer sleep (which is usually defined as >8 hours or 9 hours or longer) is associated with a higher risk of heart disease and also of diabetes. I'm not sure about damage to the brain functions, though I'm sure you could find this out easily too. This review gives an overview of studies that have investigated the association between sleep duration and cardiovascular disease.

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