[theatraine]

There seems to be quite a lot of information about why <7 hours sleep is bad for you, but I'm more interested in why sleep >=8 hours is associated with increased mortality.

See for example https://www.ncbi.nlm.nih.gov/pubmed/29790200 (an interesting study in itself).

I read "Why We Sleep" but unfortunately it didn't answer this question. The association could be correlational but it's been replicated too many times for me to believe that there's not something more fundamental. Perhaps there's a hormetic effect that's blunted by too much sleep similar to how HGH is bad for longevity?

[glaive123]

This is a great question.

As others said, the data is contaminated. Likely people who are sick sleep a lot more.

That said, I'm one of those people (healthy, I think) who sleeps 9-14 hours every day. My goal every night is to sleep as long as I possibly can. Nights when I only hit 9 hours is usually because I had to get up to go the bathroom.

I have Sleep Apnea but treat it with a CPAP and went from 20 awakenings per HOUR to just 0 to 2 per NIGHT. But the amount I need to sleep hasn't changed for some reason. I definitely feel dramatically more rested after sleep than I used to though.

I started using AutoSleep app with Apple Watch Series 4 and it's been incredibly interesting. It uses your heart rate to automatically track sleep without you touching the app. So far, I vary from 15 minutes to 1 hour of stage 4 deep sleep per night. The average person needs 1.5-2 hours per night so I am not hitting that. My recent 6 day average is 30 minutes. There is barely a relationship between length of sleep and amount of deep sleep. Just this week I had one night with 6 hours and one night with 11 hours, both totaled 15 minutes of deep sleep.

I'd love to compare notes with someone else who uses the AutoSleep app.

[nikkwong]

Just went ahead and bought a series 5 Apple Watch because of this comment. I have a long tumultuous history with sleep apnea and have been desperately trying everything to figure out how to improve it. I typically sleep 10 hours per day (the sleep apnea is that bad), so I'm going to start recording with the app you've mentioned and see what happens. Thanks so much! Feel free to each out to my email in bio and we can start comparing once i have some data.

[epmaybe]

How do you know you are healthy?

Edit: This isn't meant to be accusatory, I'm just curious

[artifaxx]

Correlation vs causation leaves a lot open, chronically sick with a number of illnesses people may sleep more. Their mortality risk is also higher. I'd wish we could see controlled studies that randomly assign people to different sleep durations. You also have to control for gene mutations that affect sleep requirements https://www.scientificamerican.com/article/genetic-mutation-...

[theatraine]

It's certainly possible that the relationship is not causal and can be explained by correlations with depression, unemployment, sleep apnea, etc. However I'm not aware of any study that definitively proves this. It would be great to see a study similar to what you propose.

In general I'm fascinated how too much of a good thing leads to increased mortality and small amounts of a bad thing leading to increased longevity via hormesis and would love to see if the same extends to sleep.

Some examples of hormetic longevity influencers: caloric restriction, alcohol consumption, exercise. Even DNP a straight up poison has been shown to be increase lifespan in animals provided the dose is small.

[dplgk]

On a related note, I wear a fitbit and if I sleep from say 12-8, you'd think this would be 8 hours of sleep (as recommended) but I usually have about 1 hour awake or restless (according to the fitbit). So fitbit says I got 7 hours of sleep.

The question is do these studies account for this supposed awakeness that seems to be part of everyone's night of sleep? Surely nobody that reads them thinks they need 8+1 hours when the study says 8 hours is good...

[dwd]

I think most recommendations are to get 4-5 sleep cycles a night, so the actual elapsed time will vary for individuals.

The problem with chronic sleep deprivation is that you miss one or more cycles, It's like if you washed your clothes but skipped the rinse and/or spin cycles. Skipping a whole night of sleep and you're still wearing yesterday's clothes.

[RandomThrow321]

He didn't answer the question directly, but he did have a possible explanation that's at least worth a mention.

In the book, he suggested that many of the studies detailed people with preexisting disease, which was the hidden variable for both an increase in sleep length and an earlier mortality.

[4ntonius8lock]

I read the original article and the abstract of your linked study.

First, I'd like to see a breakdown of 8 hour vs 9+ hours instead of grouping them. Someone sleeping a healthy 8 hours and someone sleeping 12 hours are very different.

There might be issues like, people who sleep 12 hours are sick, and that's WHY they sleep 12 hours and they die due to their illness.

Overall I'm guessing people who sleep a lot per day aren't very active, both career wise and going out/excising (just my guess) - and people who don't have jobs and are poor, they live less than people who do have jobs and have money. Also people who are depressed sleep more. So not all sleep is equal.

It's hard to approach health from a cybernetic point of view, but I think that's what's missing to make these studies less unidimensional. The key is how to make science more cybernetic. That I don't know.

[xyzzyz]

Maybe sick people just stay in bed more, which leads to sleeping more?