Even if sleep works the way you suppose, this analogy looks like apples and oranges, so I don’t like it.
With fasting, you can infer that it’s harmless just by knowing that (1) the average lean human has fat reserves to last three months, (2) total fasters don’t go through some calamity like losing lots of muscle protein (if they did, there’d be unambiguous results everyone knew) and (3) in the EEA it was probably common to have periods of scarcity such that you go several days without finding food. In other words, fasting was about as unusual as, you know, cloudy weather. These observations are already strong enough evidence to me that I consider this topic “done”—I will be surprised if a RCT shows it to be harmful, and I’ll need a deep meditation on where I went so wrong.
With sleep, it’s not so clear, because… unsourced claim here, but The Primal Blueprint among other popular books have claimed that an average “working day” in the EEA was less than ~2 hours, or at any rate shorter than a modern working day. That’s a lot of free time for sleep!
That ~2 hour figure can certainly be unpacked: does idle foraging while on a walk with your friends count as “work”? But neither sleep nor work-time seem like resources to be conserved in the same unambiguous way as calories. Sleep or no, bodies need downtime after extended exertion, and they may as well take a nap then. Wakefulness or no, there may be nothing useful to do at certain hours of the day, so we may as well sleep extra. So the amount we slept may have been quite open to modulation by external influences.
This can still back up the idea that you can subtract a few hours off your sleep need with the right stimulus—I just think that an analogy with fasting is a type error. In particular, the sub-analogy that feeling sleepy would signal something good.
Another problem with the analogy. People who fast regularly will tell you that they usually don’t feel hungry. So if you like the analogy, you also shouldn’t usually feel sleepy.
We may be “anthropomorphizing” hunter-gatherers when trying to place anything they do into our category of “work,” hence the wide variability of opinions as to how much work they really do. They are either engaged in activity conducive to survival (including things like playing, socializing, dancing, and exploring) or they aren’t. Foraging while exchanging information with friends is certainly beneficial for hunter-gatherers. I agree that, through my own lens, this activity appears fairly idle, but that’s because my cultural ideal of work is fast, energetic and high output. But if you’re foraging, it’s more efficient to move slowly so that your brain has time to recognize all the edibles you pass by. And listening and talking doesn’t seem to interfere too much with visual processing (or else there would be a lot more car accidents), so why not kill two birds with one stone?
On the analogy with fasting,
Even if sleep works the way you suppose, this analogy looks like apples and oranges, so I don’t like it.
With fasting, you can infer that it’s harmless just by knowing that (1) the average lean human has fat reserves to last three months, (2) total fasters don’t go through some calamity like losing lots of muscle protein (if they did, there’d be unambiguous results everyone knew) and (3) in the EEA it was probably common to have periods of scarcity such that you go several days without finding food. In other words, fasting was about as unusual as, you know, cloudy weather. These observations are already strong enough evidence to me that I consider this topic “done”—I will be surprised if a RCT shows it to be harmful, and I’ll need a deep meditation on where I went so wrong.
With sleep, it’s not so clear, because… unsourced claim here, but The Primal Blueprint among other popular books have claimed that an average “working day” in the EEA was less than ~2 hours, or at any rate shorter than a modern working day. That’s a lot of free time for sleep!
That ~2 hour figure can certainly be unpacked: does idle foraging while on a walk with your friends count as “work”? But neither sleep nor work-time seem like resources to be conserved in the same unambiguous way as calories. Sleep or no, bodies need downtime after extended exertion, and they may as well take a nap then. Wakefulness or no, there may be nothing useful to do at certain hours of the day, so we may as well sleep extra. So the amount we slept may have been quite open to modulation by external influences.
This can still back up the idea that you can subtract a few hours off your sleep need with the right stimulus—I just think that an analogy with fasting is a type error. In particular, the sub-analogy that feeling sleepy would signal something good.
Another problem with the analogy. People who fast regularly will tell you that they usually don’t feel hungry. So if you like the analogy, you also shouldn’t usually feel sleepy.
We may be “anthropomorphizing” hunter-gatherers when trying to place anything they do into our category of “work,” hence the wide variability of opinions as to how much work they really do. They are either engaged in activity conducive to survival (including things like playing, socializing, dancing, and exploring) or they aren’t. Foraging while exchanging information with friends is certainly beneficial for hunter-gatherers. I agree that, through my own lens, this activity appears fairly idle, but that’s because my cultural ideal of work is fast, energetic and high output. But if you’re foraging, it’s more efficient to move slowly so that your brain has time to recognize all the edibles you pass by. And listening and talking doesn’t seem to interfere too much with visual processing (or else there would be a lot more car accidents), so why not kill two birds with one stone?