I wonder how much of this is driven by confounding variables they haven't accounted for.
They do factor in shift work as a categorical variable, and employment status as a categorical variable not taking into account occupation. But probably occupation (not a variable here) interacts with sleep status. Any job that involves a lot of flying (pilot, crew, people travelling for business) get more cosmic radiation exposure, for example, and potentially more sleep disruption. Certain operations and manufacturing jobs correlated with exposure to carcinogens also likely correlate with less regular sleep, possibly in a way that isn't corrected for by the limited shift work categories.
Couldn’t this effect be classic cause vs correlation?
Perhaps someone who has a consistent schedule is hypothetically more likely to make healthier choices on average?
As someone when a poor sleep schedule, the inability it stick to a routine in this area tends to show up in every area… exercise, diet, etc.
I would imagine that someone with a very regimented life tends to stick to a lot of healthy habits. They aren’t going out to the bar every night, then waking up at 6am for their morning routine.
tfa: "Results were adjusted for age, sex, ethnicity, and sociodemographic, lifestyle, and health factors"
Would love to see a causal model [0] to help better understand all of the mediators considered as well as confounders. I'm close to finishing up an interesting read from Judea Pearl/Dana Mackenzie - The Book of Why: The New Science of Cause and Effect [1]. Talks alot about Causal Models, Causal Inference, the 3 ladders of causation, etc. I liked the graphical approach to help outline exactly how one thinks about direct and indirect effects and how it facilitates counterfactual analysis and causal mediation analysis.
Sometimes it is a cause vs causation. Sometimes the scientist didn’t adjust for a variable that clearly would impact both fields they were measuring. To make such a claim, I think it’s appropriate to name that hypothetical third variable. Otherwise the comment is so general it applies to all statistical studies.
Did they explain how exactly they adjusted those results?
Or maybe if you are sick you don't sleep as well.
Pretty much my thoughts. People in lots of pain don't have a regular schedule to do anything, including sleep.
As always with a lot of these: it's not saying causation.
You might measure the speed of your car by putting your hand out of the window and notice that the wind force on your hand is strong when the car goes fast.
Putting your hand out of the window and then blocking the wind with a book doesn't make the car slow down.
Keyword: "associated"
EDIT: I meant to communicate that it doesn't make the car slow down as much as your hand behind and blocked by the book (feeling almost no wind), would imply.
Racing stripes would be a better example. Though negligible, a hand out the window does have a causal impact on speed.
On the other hand racing stripes have zero impact, but do correlate to the speed of the car.
What about speed holes?
Bad example because yes it does make the car slow down.
Original comment assumes the size of my hands is not 50m^2. Very presumptuous.
I think the point is that while it does act as negative acceleration there isn't a causal relationship with the actual speed of the car, which is mainly related to how far the gas pedal is pressed.
Drag is a causitive input to speed though.
nextCarSpeed(currentSpeed, wheelPower, dragForce, mass, deltaTime) =
currentSpeed + ((wheelPower / currentSpeed - dragForce) / mass) * deltaTime
Initially I assumed it to be negligible but the numbers are actually very close!
I calculate around a 3% drop in speed (from 60mpg) for holding an average sized book out of the window. That's surprising to me.
It's not quite right to use hazard ratios to calculate life expectancy. But if we force it, it looks like being in the top 20% of "regular" sleepers compared to the bottom 20% confers 3-4.5 years of extra life (from birth, assuming everything else equal, assuming USA, etc.). That's 3.8%-5.7% more life (79 year life expectancy at birth in the USA as of 2025). So the numbers are actually close.
I made a bad analogy :)
But you get my point!
But what color is that bike shed ??? /s
Maybe you can't stop the car that way, but if you feel that kind of wind on your hand you should worry that your car is going fast.
> ... you should worry that your car is going fast.
Only if we know of an intervention that will likely slow the car down and the risks+cost of that intervention justify the benefit.
Otherwise, we worry without purpose.
EDIT: I will say that there is a philosophical question here related to "basic research" / "pure science" / "fundamental science." Usually just "knowing new things" eventually proves valuable, especially in a long timeline. So in that sense, TFA could be important.
>Putting your hand out of the window and then blocking the wind with a book doesn't make the car slow down.
...yes it does?
The study is clearly about correlation and not causation, but still the term "important predictor" keeps triggering me. People can't sleep due to stress or noise or disease (e.g. coughing), and while "predictor" seems to be normal science lingo I feel it nudges the conclusion of this study into the direction of causation instead of very clearly saying that it is pure correlation.
Nobody goes to bed and wants to wake up 2 hours later.
But they choose to. Alcohol, caffeine in the afternoon, just not realizing blackout curtains matter, lights or displays on in the room... you can't help someone who isn't making bad choices, but most people can make simple choices that improve their sleep a lot!
This makes sense to me as a correlation. Mental health disorders alone seem like they’d contribute significantly.
ADHD, for example, is correlated with both sleep cycle issues and worse outcomes in life (including higher rates of crime and participation in risky activities).
I kinda realize that the most important factor for personal success (whatever kind of success you want) is mental stability.
Like, John Carmack said that he NEVER burned out, never went into a dark corner (verbatim from his interview), and everyone agrees that he works like a machine. And I don't think he actually spent a lot of mental training to achieve that stability, because, he has been like that from a young age. This is THE best thing you can have in the world, if you want to achieve something, anything. If you don't have the mental toughness, you won't be able to make through that 10,000 hours (cliche, I know). I guess that's also why many self-help book talk about being consistent -- to be consistent, is to have mental stability. And I think there is a whole difference, between someone who trains his mental to stay stable for 6 months, then collapse, from someone who actually doesn't need to train and just be stable somehow.
This also leads me to realize that good sleep is one of the fundamentals of a stable mind. As a parent, I actually don't remember when was the last time I had a good sleep, and my definition of a night of good sleep is perhaps just trivial for someone else. At the same time, I consider myself lucky, because at least I don't suffer from serious mental issues. I still have a job and a house, and that's better than many out there.
This then leads me to despise the human body. It is a machine so delicate that you have to be very lucky to be super productive, whatever your definition of being productive is. It seems to ignore the input in short term (e.g. you can eat garbage food for a month and nothing really happens, or, you can sleep 4-6 hours every day for the last 6 years and still function normally), but once the long term shows up it is very hard to reverse. And there are so many theories focused on it that we have no idea which one is best for the individual. You might as well spend years doing A/B test on yourself and still have no idea what the hell is going on. Or you need to be super rich to have some medical team monitor you 7/24 to figure out what the hell is going on.
I sometimes think about the same. Its a sad truth that if you bad days those days may be at the worst moment. Sleep definitly helps for a good mind but also exercise!
Carmack always seemed to have a really strong idea on what was important for him to work on. How much of that is mental toughness vs having a believable purpose?
Believable is important because you have to internally 100% without a doubt believe that what you're doing is the right thing to be doing now.
As soon as the "what ifs" starts to creep in for the big picture items or goals, that can destroy everything. I'm not talking about running into technical implementation problems along the way (those can be fun), it's more like "did I pick the right language for this?" level of questions that sit in the back of your mind.
Personally when I find something to work on that I like and will have what I think is a favorable outcome, it's easy to put in 8-10 real 100% laser focused hours into a task every day, even if it spans weeks or months. I'd like to think most people can do this too, the hard part (for me at least) is having these things to work on.
Well that sucks, given I have a gene variant related to delayed sleep according to 23andme.
Last year I did an experiment of sorts while unemployed for a time and found that if I just slept and woke when tired that my sleep time would naturally recess and eventually "flip" after about a month.
My entire life I've wondered why I feel incredibly tired and found waking up so difficult. Turns out that if you follow your bodies dominant sleep cycle it's a synch to wake up. Unfortunately, it doesn't work with modern life very well.
I've found my sleep regularity to be pretty malleable. It can become a habit. When I was in grad school I went to bed at midnight and woke up at 7am. Once I started running more in the mornings, I gradually shifted to going to sleep at 9pm and waking up at 5am.
The first couple days or week will feel pretty bad, but if you give yourself enough time then you'll shift your sleep schedule around. Now I get tired at 8:30pm and fall asleep at 9ish like clockwork. grad school me would have considered that insane considering I'm doing less work on average during the day. My day is just shifted now so that I do more stuff in the mornings and really relax in the afternoons, which is the opposite of before.
A key is actually giving yourself enough time to fall asleep. Most people think they can hop into bed and just get 8hrs, when you actually need to hop into bed around 30mins beforehand and really relax with a book or something.
I also think it's important to not stress about sleep a lot. Unless you're literally feeling miserable or have apnea, I think it's better to just let yourself relax if you wake up in the middle of the night. Sometimes I'll snap awake at 2am and just read for 2hrs, then get 2 more hours of sleep and generally feel fine.
People are different. What you find easy and trainable, someone else will find it doesn't require training and someone else will try as hard as they can and won't succeed.
I also have sleep drift problem and consistenyly had it for the past 7 years.
I discovered that it helps when I actually put in effort to fix my sleep schedule. Like getting off screen 1 hour before I sleep. Boxing bedtime to 23:00-08:00. And similar things.
It is just really difficult to fix for me but it doesn't feel impossible. I have made progress in last 6 months but trying different methods and only some portion of that progress stays permanent.
Also have the same experience fighting depression-like symptoms and anxiety. It just takes a lot of time and is difficult. Some people just don't have these problems and I do but this doesn't mean I am genetically attuned to be like this and I can't do anything. It is just difficult.
Good points, if I am careful about caffeine and do all of that it's not unmanageable. Being outdoors and camping and getting good physical activity is the best I found. But it's a struggle for me.
> Also have the same experience fighting depression-like symptoms and anxiety. It just takes a lot of time and is difficult. Some people just don't have these problems and I do but this doesn't mean I am genetically attuned to be like this and I can't do anything. It is just difficult.
Should I mention that "neurodivergence" and different sleep pattern genes have a large co-morbidity? E.g. many people with anxiety / ADHD / dyslexia / depression / etc have a very high likelihood of having delayed sleep or other genes.
I have had a similar experience. I would find my sleep schedule constantly drifting later and later, which made it harder to wake up in the morning, so I would self medicate with caffeine which made me anxious, which contributed to the same cycle. But even when I stopped taking caffeine I always found it difficult to actually go to bed at the same time every day.
What finally worked for me were red light glasses. I wear the True Dark Twilights Classics (though I’m sure there are other brands on the market) for 2-3 hours before bed time and I’m actually sleepy. Way more effective than taking melatonin tablets ever was in my experience. And I haven’t even had to substantially change my screen usage either (though the glasses do make everything come out monochrome, which makes it difficult to use anything that’s not in color blind mode).
As my diabetes has progressed, I find myself sleeping more odd hours (it can be hard to fight off the tiredness that comes after a meal), and I can be frequently woken up my extreme lows where my body is screaming for carbs.
because of how we evolved biologically, there are some processes, particularly in the brain and not just the body, that can only happen during sleep
like "garbage collection"
Well, I'm screwed...
My thought exactly. For people who struggle with this, and conventional wisdom doesn't seem to stick, what are we supposed to do?
Lifelong severe insomniac (sleep onset mostly) and cured myself pretty much entirely over the last year or so. My suggestions in order of what I perceived to be their cost vs effectiveness ratio:
1. The Sleep With Me podcast, especially if you struggle with racing thoughts (if you have a partner who can't stand hearing this, the Ozlo Sleepbuds are a good if imperfect solution)
2. Stellar Sleep, an app that delivers CBT-I, evidence-backed cognitive therapy for insomnia; this reset my sleep clock in about two months, which is now maintained by the other items on this list
3. Eight Sleep mattress pad to keep temperature low during sleep, especially on warmer nights
4. Manta Sleep Mask to get full light blackout
Also I've definitely just doxxed myself. But worth it to help some fellow insomniacs!
Don't watch any kind of screen in the evening. Read a book instead. You'll fall asleep sooner.
Isn't that "conventional wisdom"?
I do watch screens in the morning, but reading in bed (though still a screen, Kindle) still knocks me off in max 15 minutes. I would love to know why... I only know it works.
Could be related to the light spectrum. Kindles aren't really "screen" like the others; they do have background light but you can turn it off and use it with its paper-like screen (which is what I do and really like it). But traditional screens have blue light as part of the normal light they emit, which is known to disrupt sleeping patterns. When I am using my cell phone or computer right before sleeping, I usually turn on colour filtering to make my whole cell phone be tinted red. This helps wonders. I found this page that explains how this can be done: [0].
[0]: https://ios.gadgethacks.com/how-to/keep-your-night-vision-sh...
Conventional wisdom does work for me but it is immensely difficult. I would say take the advice seriously but don't take the timeframe or problem difficulty assesment coming from other people.
It is only natural that it takes months to years to fix a problem if you had the problem for years.
The only thing that worked for me was having a kid. He wakes up early every day, so I have no choice. Taking care of him is so taxing, being sleep deprived isn't on the table.
What's more, you have little difficulty falling asleep any time, any place!
Did you cut out all caffeine?
> conventional wisdom doesn't seem to stick
I wouldn’t say cutting out all caffeine is conventional wisdom. Every sleep physician (sample size of 3) I have talked to has basically said it’s not great but if you only drink it early in the day it’s probably fine.
Let's create a Discord/Signal/WhatsApp/mailing list group to help each other figure it out... it's time to end our sleep irregularity once and for all!
Hard to answer precisely without knowing what conventional wisdom didn't stick.
The common levers I know and that worked at least a bit for me:
- start by having a fixed waking time, and get sunlight or bright light quickly after waking up. Normally relatively fixed sleep time is supposed to follow. For me waking up is the easy part, transforming that into getting up and going outside is harder. Another option here is a strong (like, really strong) lamp on a timer, or letting the morning light in your bedroom (this one is usually not recommended I think, most people seem to be blackout curtains style, but for me it gave me a nice 6am waking time with good sleep last summer).
- melatonin. Two main ways: using it as a kind of hypnotic, so ~30 minutes before sleep, experimenting with 0.3mg to ~2mg doses ; then using it as a circadian regulator, this is a good resource https://lorienpsych.com/2020/12/20/melatonin/, search for "TO TREAT" in the page.
- app timers, for me it was mostly no twitter and no youtube, or a very low time for each.
- light, ie reduc light before sleeping. Not just blue light and not just screens, if I'm on my phone in bed I'll reduce the luminosity a lot, same with computer, same with e-reader. I also try to avoid using too much the lights in my room. More light tend to make me feel more "wired" and less ready to sleep.
- "meditation" to cut rumination, by which I mean "lay down in my bed, gently try to find sensations in the body and to stay focused on them, by gently I mean it's a very low stakes game where the goal is to find sensations in the body and give them attention, but losing focus for a while is not a big deal".
- shower in the evening, as I don't like feeling dirty when I am in my bed, but also not just before bed as sometimes I don't really want to go take a shower and this delays my bedtime
- clean bedsheets, bedroom, stuff in/on your bed
- AC in the summer, I wouldn't be able to sleep properly without it
- sleeping mask. It helps going to sleep, but it falls of my head every night so it doesn't prevent waking up with light too.
- making getting good sleep the priority of the evening. This is easy/possible for me due to my circumstances (ie low responsibilities in the evening). The way I do it is that unless something is actually important, what I'm trying to accomplish in the evening is prepare myself for sleep and get good sleep. This can look like not starting a movie at 11pm, not booting up games, not eating a super heavy meal, not drinking too much water after 6pm to avoid waking up to pee, if I have things I want to do try to do them early so they're done earlier, move some stuff I want to do every day like spaced repetition in the morning.
If it's of any help to you: if TFA is true, I should be dead already. I've got the absolute most fucked up sleep schedule. Thankfully I've got a lovely wife who accepted it (to be honest as it's been like that since I was 20 y/o, she knew...).
To me burning the midnight oil is my way of life.
In a past life, two decades plus ago, I used to write books: I'd write at night, when all is quiet. I'd go buy two or three warm "croissant" at 6:30am when the shop would open, then I'd go to bed.
And I love the hours later at night that then becomes early in the morning to get work done.
Because I'm such a night owl (not to party nor drink at all), I've got a different view on, for example, city life. Or rural area life. Things are different in the middle of the night.
Last night I had something that needed solving: went to bed at 8am.
My wife shall never ever take an appointment for me in the morning.
If it's of any comfort to you, I'm still fit and made it to 53 y/o so far and my doctor laughs at me when I go see him, saying I'm totally fine.
Anyhow seeing the old wreck my fater is at 78 y/o, I kinda came to peace with the notion that it's okay'ish if I don't make it that far.
Those with fucked up sleep schedules: you're not alone.
P.S: if I wasn't such a night owl, I'd never have met my wife... Long story but the butterfly effect: 25 years ago, coming back from my editor (who was also a night own) at something like 3am I decided to stop at a club knew but to which I'd never been, for there was some forms of life still awake too. There I met a girl, which became my girlfriend for a while. I kept in touch with her and through her I met a friend: a crazy dude. And through that crazy dude I met my wife. So had I not decided to stop at 3am at that club, I'd never have met my wife. So there's that.
Are you? Would be happy to die by 65-70 instead of struggling through 80s…
No one knows for sure how they will be in their old age. My grandmother didn’t seem to struggle until her mid to late 90s. That’s a lot of years to leave on the table. Years that allowed her to meet and enjoy time with her children, grandchildren, and great-grandchildren.
Had she died at 65, I wouldn’t have even known her. Instead she was around for my entire childhood and well into adulthood.
I'd rather live through my 80s without much struggling. Longevity and quality of life until the end. And I try to live in the way that lends itself towards that.
Easy to say when you're not 65-70.
Interesting, though it seems quite annoying to read research papers with all that jargon without using an LLM
Research papers are written to be read by other researchers, not laypeople. If you have no scientific background and want to read up on a topic that you are not familiar with, you'll have to find other sources of information.