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Comment by enceladus_ice | Hacker News Reader

I recently listened to an interview with Matthew Walker (author of "Why We Sleep" book mentioned in article). Dr. Walker stated the scientific consensus is now trending toward historical biphasic sleep being a social trend rather than how we're "supposed" to sleep.

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Matthew Walker's excerpt on biphasic sleep: https://delanceyplace.com/view-archives.php?p=3524 TL;DR: There's evidence of cultures untouched by electricity sleeping 7 hours at night with a 30-60min afternoon nap, which he calls biphasic sleep, with some tribes switching to monophasic in cooler months. All humans have a hardwired dip in midafternoon alertness.

I believe the original parent is refering to the idea that people naturally wake up and do stuff in the middle of the night.

Yes, but I couldn't find where Matthew Walker says that.

> All humans have a hardwired dip in midafternoon alertness.

In my personal experience, if you don't have a post-lunch carbs crash and you do have air conditioning, the dip doesn't exist.

He doesn't really seem to back up the existence of a biological dip at all that is innate to human rhythms.

Isn't he claiming the opposite? (But I don't have the book to dig into the sources):

This brief descent from high-degree wakefulness to low-level alertness reflects an innate drive to be asleep and napping in the afternoon, and not working. It appears to be a normal part of the daily rhythm of life.

I've always understood it to be related to the hottest part of the day, not so much a post-lunch thing. Probably why GP mentioned air conditioning preventing it.

True, I was referring to waking up in the middle of the night for an hour or two and then going back to sleep.

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