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Comment by coldtea | Hacker News Reader

>Sleep is not like the bank, so you can't accumulate a debt and then try and pay it off at a later point in time. And the reason is this: We know that if I were to deprive you of sleep for an entire night — take away eight hours — and then in the subsequent night I give you all of the sleep that you want, however much you wish to consume, you never get back all that you lost. You will sleep longer, but you will never achieve that full eight-hour repayment, as it were. So the brain has no capacity to get back that lost sleep that you've been lumbering it with during the week in terms of a debt.

What does "never" here means though? Obviously you could get back to your normal self after a few days of sleeping well, no?

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This seems to contradict recent study that I came across [1]:

The mortality rate among participants with short sleep during weekdays, but long sleep during weekends, did not differ from the rate of the reference group. Among individuals ≥65 years old, no association between weekend sleep or weekday/weekend sleep durations and mortality was observed. In conclusion, short, but not long, weekend sleep was associated with an increased mortality in subjects <65 years. In the same age group, short sleep (or long sleep) on both weekdays and weekend showed increased mortality. Possibly, long week- end sleep may compensate for short weekday sleep.

[1] https://onlinelibrary.wiley.com/doi/pdf/10.1111/jsr.12712

It may be important to distinguish between (A) long-term mortality versus (B) impaired cognition and mood on a daily basis.

To use an analogy, you might be able to maintain a car so that its lifetime mileage isn't reduced, but that doesn't mean that it can't suffer in terms of handling, speed, comfort, etc.

I'm someone who often gets insufficient sleep during the week and, anecdotally, sleeping 12 - 16 hours on Friday and Saturday night seems to rejuvenate me. I've always felt like I could pay off sleep debt if I really get a lot of sleep on the weekends in proportion to how much I lost during the week.

Yeah this quote sounds like something that someone would say when they don’t actually understand the underlying system.

It doesn’t follow that if you miss eight hours of sleep you’d need 16 to catch up - maybe some processes take a standard amount of time and don’t need to be repeated, it might be more efficient when you’re already asleep to fix things in an extra two hours than an entire extra eight.

Something is fishy with the quote’s assumptions. It strikes me as something probably untrue that we’d understand with more information about what sleep is actually doing.

I'm glad other people are talking about this, because this part of the article really irritated me as well.

Building off what you said:

>It doesn’t follow that if you miss eight hours of sleep you’d need 16 to catch up

It might also be that if you miss eight hours, you can never catch up 100%, you can never fully pay off the lost sleep. It would still stand to reason that you'll be better off with X amount of "catch-up" hours, such as the extra 2 a night you were suggesting, following lost sleep than if you didn't have any catch-up hours.

So knocking down the straw man of "you can't fully repay your sleep balance" seems to be an equivocation that's just wasting everyone's time. I don't know that people necessarily think that exact thing. It's still probably better to sleep more after going without it, even if you don't literally gain 100% of the benefits back, and that's probably what most people mean.

What is meant is that there are long term health consequences of sleep deprivation and you can’t cancel those effects by oversleeping the next couple days after an all nighter.

I'm not a sleep scientist but it sounds pretty logical to me. If I'm chopping vegetables for dinner and I cut myself with the knife, it takes time to heal. But chances are it's never going to be completely healed. There will be a scar. If I cut myself with a knife then for the next few days I don't cut myself with a knife, the wound will heal but the scar will remain. I can't cut myself one day and then go several days without cutting myself and expect that it somehow cancels out the day I got cut, and I certainly can't say "eh I'll only cut myself on the weekdays and make up for it by not getting cut on the weekends". I'll still have that scar.

Brain injuries are too often discounted because you can't see them. If someone was purposefully cutting themselves with a knife we wouldn't think they were cool, we wouldn't celebrate them as heroes in our society, we would try to help them stop injuring themselves. So why do we celebrate people who actively injure their brains? Because we can't see the damage.

We actually do celebrate athletes' physical sacrifices. Think marathon runners pushing across the finish line, or a running back selling out for the touchdown. It's probably something wired into us as human beings. Just a side note. Your analogy is on point and helpful.

Very good point, thank you.

> We actually do celebrate athletes' physical sacrifices.

I'm not certain that's quite accurate. It seems that what's celebrated are their accomplishments and "sacrifices" in the sense of effort and self-denial, but not injuries.

The sentiment around brain injuries that professional boxers (and, more recently, American Football players) suffer from isn't what I would characterize as celebratory, for example.

Even temporary injuries can be met with disdain by fans of team sports, as it could take the whole team out of the running for that entire season.

However, I'm far from intimately familiar with athletics, so I'd genuinely welcome being shown counter-examples.

That concussion sentiment is very, very recent. Hard hits in football and boxing were absolutely celebrated as a show of dominance. They still are, just with obligatory lip service paid to hoping the player is ok.

I don't think disdain is the right word. Disappointment can certainly come into play, but look at any serious injury on the court or the field. What happens when the player is able to limp off, or is even carried off? Applause, sometimes a standing ovation, for the player's physical sacrifice.

I believe this is tied into the same primal urges that make us love a compelling war movie (we used to celebrate war much more than we now do as well), or want to work 16 hour days for the chance at striking it rich.

> lip service paid to hoping the player is ok.

If we're talking about "celebrating", lip service is all I can think of that fits the bill. People enjoying it in the privacy of their own thoughts isn't the same thing.

> look at any serious injury on the court or the field.

That's why I was asking for counter-example. I don't have this experience. I was hoping for, possibly, media coverage or maybe fan blog posts or videos.

> Applause, sometimes a standing ovation, for the player's physical sacrifice.

If I were to witness this from afar, I would have no idea what the applause is for, so, again, I'm looking for that evidence. A more charitable interpretation would be that the applause is due to relief that the injury could be walked away from or even gesture of support in recovery.

If you lose a piece of an old memory from sleep deprivation, you are not going to magically get it back once you catch up on your sleep. It has happened to me when I pulled all-nighters. I just couldn't remember that friend's name or that old password.

And you still don't remember that friends name?

> And you still don't remember that friends name?

Some information can be relearned. Some cannot. It would be relatively easy to discover the name of someone from your past (ask a coworker, check a yearbook). I think the better example in the parent’s comment is a lost password.

I changed the pin on my phone while I was in a sleep deprived state and had to erase it to recover from not knowing the pin after I finally slept.

I don't think you're relearning your friend's name so much as reminding yourself. You haven't lost the memory, you just can't bring it up in that moment. And given time you might remember. But it's a bad example like you said.

Maybe you should see a doctor if you're forgetting your friends' names.

I think there are two things: the short-term effects of missing a night of sleep persist for several days even if you get plenty of sleep later and the chronic effects of missing a day of sleep accumulate even if you "make up" the hours later on.

I'm guessing the second one is what the article is trying to say here. If you don't get enough sleep during the week, you can't make it up on the weekend, even if the total hours slept per week adds up. You'll still suffer the long-term effects of chronic sleep deprivation.

This sounds like a confused retelling of the actually true fact that you can't sleep sixteen hours on the first night, then go without sleep entirely on the second night without any ill effects (on the theory that you have 8 hours of sleep "saved up"). Sleep is not like a bank in that sense.

Yeah this is one of those oft repeated pieces of advice that has never made sense to me. It's always worded such that it sounds like the effects of any sleep deprivation ever are permanent.

I guess what they mean is that if you don't sleep for 24 hours and the next day you sleep for 16 (to make up for the lack of sleep in the previous day), after you wake up you still wont be as good (mentally, immune-wise, etc) as you'd be if you've slept properly on both days.

Obviously that can be corrected over a few days period and you get back to normal (except if you had abused yourself will lack of sleep over many years, in which case you might have indeed incurred some permanent damage).

He seems to be saying that you won't sleep for 16 hours the second night.

Well, as for that, you'd be surprised.

Of course they are.

You'll learn less in your sleep deprived states, Which are days you aren't going to get back. Your sleep deprived self will also be better at creating tech debt, which takes away time from the future.

>You'll learn less in your sleep deprived states, Which are days you aren't going to get back.

That's not what a description of what the professor says in the article, or the way we mean it.

Of course you won't get "chances to learn" or "tech debt" back. This is not about it. TFA talks about a physiological debt that you can't repay.

I don't know how to measure the physiological debt, and the person asking the question was not sold on the physiological debt.

That is an odd perspective. That's like saying that the damage from a twisted ankle is permanent, since you'll never get back the two days of lost activity.

From that point of view, all injuries are permanent.

Well, yes. But the difference comes in the nature of the deficit you can't get back.

By not sleeping, you magically turn some fraction of the previous day's learning into wasted time, just throw it away.

The appropriate analogue in the twisted ankle case would be if the twist magically "un-walked" the 4 miles you walked the day before, and that increment of weight loss and cardio health were lost to you. This is of course not the case.. :)

You generally don't recover fully from twisted ankles. Most injuries are in fact permanent in a certain sense. You heal, but not 100%.

I saw this analogy upthread, and it's changed how I consider sleep deprivation. Brain injuries may not be different from physical injuries.

> all injuries are permanent

Most significant injuries I've sustained since my early 20s have not let me completely forget them, in spite of them being "fully healed".

Every single day is a unique and precious moment in time; spending that day sleep deprived has many disadvantages from a human's perspective. You might have caught a cold you otherwise wouldn't have, or been slightly less emotionally stable during an argument with loved ones and been overly harsh, or any other number of things where if you'd been well-rested, you would have been Better. Oversleeping the next night and undoing causal effects of that short sleep day can never be reversed, both external and internal to the body.

The benefits and effects of sleep are many and I highly recommend reading his book, after which you too will probably agree, you can truly never get it all back, not even close. One fine example that blew my mind was that getting your flu vaccination the same day as getting short sleep will effectively short circuit your immune system's ability to integrate the vaccination, making it much less effective that you're vaccinated for that strain(s)!

His book represents to me a paradigm shift in understanding of what sleep even is. We sleep so that we may live, not the other way around.

Clearly it's exaggerated bullshit.

People put themselves through hell all the time; I'd be dead if you could 'never repay the sleep debt'.

They should focus on how miserable sleep deprived people become - that's a real, un-repayable cost.

This might not be true... http://www.health.com/sleep/sleeping-in-weekend

Even that article says that, though catching up on the weekend is better than not trying to catch up at all, consistency (i.e. not falling behind in the first place) is best.

Do you need 16 hours the next night after losing 8 the first night? What happened to "Sleep is not like the bank?" If it's unlike the bank in your ability to pay back, maybe it's also unlike the bank in the bank's need to be paid back. Seems weird of them to frame the point using a bank analogy they just said was inapplicable.

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