129: How Humans Actually Slept!

Speaker: What if I told you that the way most of us sleep, eight straight hours, lights out, alarm at six is actually a pretty recent invention, and for the vast maturity of human history, people slept in a completely different pattern. One that the signs suggests might be better for your brain, your mood, and your hormones.

So today we're going. To deep dive on ancestral sleep rhythms, split sleep, biphasic patterns, the lost art of the nap, and how to actually apply any of this to a modern life that was not designed with your biology in mind. Welcome to the Primer Shift podcast. So let's jump right in, and here is a question worth sitting with.

Where did the idea of one long, uninterrupted block of sleep actually come from? Most people assume it's just natural biological, the default human setting it is not. Historian Roger Eckert, and I hope I'm not butchering that name, spent 15 years combing through pre-industrial diaries, medical texts and literature, and what he found was extraordinary before artificial lighting took over in the 19th century.

The dominant sleep pattern in Western Europe was segmented, sleep first sleep. And second sleep. People would sleep for three to four hours, then wake naturally for one to two hours, then sleep again until dawn. That wake period wasn't insomnia. It was just part of the night. People used it to pray, talk, read, interpreted dreams.

Medieval medical text actually recommended as the best time for intellectual work. And psychiatrist Thomas Ware confirmed this experimentally in the 1990s. He put subjects in 14 hours of darkness per day for a month, and within weeks, almost every single one of them naturally shifted into this exact biphasic pattern.

This is in a fringe theory that that evidence is pretty solid. Now, here's the modern kicker. And when people experience that middle of the night waking today, they panic. They check their phone, they catastrophize, they doom scroll. What once was a calm, even sacred part of the night has become a source of dread.

We've pathologized something that used to be completely normal. Now I want to pause and talk to a specific group of people. Some of you're listening to this and thinking, that's not me. You go to bed, you fall asleep. You wake up eight hours later feeling great. Maybe you get up once to use the bathroom like I usually do, but you're back asleep within two minutes, no effort.

Is that you? That's good. Generally good. Here's the thing about everything we're discussing today. It's not a prescription, it's a permission structure. The whole point is to stop. Pathologizing things that are actually normal and that includes your pattern. Consolidated sleep. One long, uninterrupted block isn't wrong.

If you're waking up rested and functioning well, that is the only benchmark that actually matters, that biphasic research isn't telling you to change something that's working. It's telling you that if you wake in the middle of the night and can't go back to sleep that night might not be insomnia. It might just be your biology doing something old, but if you are back asleep within two minutes.

Don't mess with it. What this conversation does offer you, even if your nights are solid, is a lens for the rest of your day that afternoon. Energy crash, that's real biology, not laziness. Your chronotype, whether you're a morning person or a night owl, it's largely genetic and fighting. It has a real cost Take.

What's useful from today. And just leave what isn't, as with all of my episodes, really, here is where it gets satisfying though, because the biology doesn't just allow for these patterns. It almost seems to expect them. You've heard of circadian rhythms, I'm sure, your 24 hour internal clock, but there is a second system called the ultradian rhythm.

Those are shorter cycles, roughly 90 minutes each, repeating across day and night. During sleep, you cycling through 90 minutes arcs like light sleep, deep sleep, REM sleep, and during the day your alertness follows the same oscillation and right around the middle of the day, six to eight hours after waking, give or take, there is a predictable trough.

We talked about this in a previous episode about napp. And sleep researchers call it the post lunch dip, but it happens whether or not you've eaten lunch. It's built into your rhythm. And I highly recommend to check out the previous episode on mapping to learn more about exactly that dip and how to leverage it.

Um, but NASA has studied this extensively in pilots, and they concluded that a 26 minute nap improved performance by 34% and alertness by over 50%. A short nap outperforms caffeine without the rebound crash. And for people who experience split sleep, a hormone called prolactin linked to relaxation, immunity, and creativity spikes during that middle of the night waking window, which may explain why people historically described it as meditative and emotionally clear.

The brain chemistry during that window is genuinely distinct. So let's get practical with two templates and then you can pick the one that fits your life, if any, if either of those fits your life. T

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Now back to the episode, and the first template is split nighttime sleep.

You know, it's, and this one is, I think, best for people who already wake up. In the night or anyone with a flexible schedule. And the structure can look something like this. You know, you first sleep from 10:00 PM to around 1:00 AM and again, those are not set bed and wake times. Those are just patterns.

Shift them around as you see fit, depending on when you go to bed. Um, and when you naturally wake up. If you do wake up. But for the sake of this experiment, or for this example, let's call a first sleep from 10:00 PM to around 1:00 AM. And then you might have a waking period from 1:00 AM to two 30, so roughly 90 minutes.

And then you have your second sleep from two 30 to six or 7:00 AM And the key here really is if you wanna embrace this template to stop treating the waking as a failure, the moment you get anxious about being awake, your cortisol rises and you've sabotaged the window. What I recommend is to keep lights very dim or.

Turned off completely and then do something calm journal, read on paper, stretch, quiet conversations. No phone, no email, nothing that can potentially stimulate you. And after 60 to third and to 90 minutes, you should feel the pull of sleep return. Just let it. And the way you start this template is by not forcing the split intentionally at first, just stop fighting your natural wake up.

Again, if you are a person who wakes up in the middle of the night, and if you wake at 2:00 AM get up, do something gentle and return when sleepy, and see what your biology settles into on its own Template number two is ache into what we discussed in a previous episode, the nap plus main sleep, and I would argue it's more compatible with modern schedules than people realize.

And the structure looks something like this. You have your night's sleep from 10:30 PM to 6:30 AM Again, that's a rough framework, not the times are not set in stone. Uh, adjusted of course, as always to your chronotype. And then the midday nap could be from 1:00 PM to one 20, I would not do later than 3:00 PM because it might then negatively impact your sleep pressure at night.

And nap duration matters. You know, if you nap between 10, 10, 20 minutes, you know, it's mostly light sleep. You wake feeling sharp, the sweet, and it's, I I would say the sweet spot for most people. If you nap for 30 to 60 minutes, you can enter deep sleep and your risk of grogginess when you wake up, especially if the, if you don't wake up, if, if you use an alarm, for example, and you wake up at the end or in the middle of a sleep, a deep sleep cycle, you'll feel it.

And it's gonna take you quite a bit to get out of that grogginess. If you nap for a, for a full 90 minutes, that allows you to go through a full sleep cycle. And that really helps, or has very strong creative benefits. But it's a time commitment. I don't have 90 minutes every day to take a nap, you know?

Now here is a trick you can leverage. I, I don't personally do it, but I've seen success in a lot of people doing that drink. A strong cup of coffee immediately before taking your 20 minute nap, because caffeine takes about 20 to 30 minutes to kick in, so you sleep through the absorption window and you wake up with a caffeine just arriving and natural adenosine cleared.

And studies have shown that this trick outperforms either caffeine or napping alone. What if you can't nap? Well, even lying down with your eyes closed for 10 to 15 minutes, you know, no pressure to fall asleep at all, produces measurable cortisol reduction and performance recovery. So you get still some benefits that are worth leveraging.

You don't have to lose consciousness, you know, in order for it to be effective Now. Whatever sleep pattern you choose, light is your most powerful lever. The ancestral baseline was pretty simple, you know, bright sunlight in the morning, warm firelight in the evening, darkness at night. That's just how it works in nature.

Unless there is a full moon and you still get some light, but most of it get the opposite di indoor light in the morning because we're indoors and we don't wanna turn the lights all the way up yet. And then bright blue screens at night. And a bedroom that's not entirely dark. And the three things to fix this in order of impact are number one, morning sunlight.

Get outside within an hour of waking, even 10 minutes, no sunglasses. This really anchors your circadian clock and sets your melatonin on. For the evening, it has downstream effects on mood and energy all day. This is arguably the highest leverage sleep habit. Most people aren't doing it, even if it's cloudy, it's brighter.

If you had a light meter, you can tell that it's brighter on the outside, even on a cloudy day in most cases than it is indoors. Number two, evening warmth. You know, two hours before bed shift toward warm light night shift on your screens. You know, I have a trick on the iPhone. Triple pressing my side button turns it red even.

Um, you know, amber bulbs or salt lamps at home, we have several salt lamps at home that we leverage. We have a, a very dark orange nightlight in the bathroom. You know, the kids have red reading lights, et cetera. If you can get away with it candlelight, you know, that's the full ancestral way of doing it. Or if you have a fireplace, turn that on.

If it's a wood fireplace, that is because the natural gas fireplaces give off a, a slightly different color If. And number three is bedroom darkness. You know, blackout curtains. Ideally, no standby lights. Tape them off if you can turn them off or unplug the device better, or yet false phone face down in airplane mode, or in another room better yet, because even small amounts of light during sleep effect, glucose metabolism, and heart rate, and before going to bed your melatonin release.

You know those aren't biohacks. They're returning to what your biology evolved expecting now. I want you, I want to leave you with something concrete. Just one thing to try this week, you know, if we, if you wake up in the night, stop fighting it. Get up, stay in dim light, or leave the lights off completely and do something gentle.

And return to bed when you feel sleepy, eventually you'll feel sleepy. But I know the feeling that, you know, if you are, I'm, I've been up now for 40 minutes, for 50 minutes for 60 minutes. Chances are by the 90 minute mark, you go back to bed again. But if you stress out beforehand, then it'll negatively impact you.

You might still fall asleep at some point. But chances are you might fall asleep even later or have increased cortisol and a higher resting heart rate and a lower HRV and all of those things that are not conducive then to getting more restore for sleep once you fall asleep again. You know, and do this maybe for two weeks, and then evaluate how do you feel?

How do you really feel during the day? Even if, if you've been awake for six to 90 minutes during the night, if you get your seven to eight hours combined sleep, chances are you will feel pretty good. And it's a less of an anxiety inducing lifestyle at the end of the day. And if you've never napped, you know, try a 15 minute.

Rest between one and 3:00 PM three times this week. No pressure to sleep. Just rest and notice how your afternoon feels and no matter what else you do. Get outside within 60 minutes of waking tomorrow morning, 10 minutes. Just stand in the light, do it for a week and see if anything shifts. Your sleep doesn't need to be fixed.

It might just need to be understood. So thanks for being here. If this resonated, share with someone who's being been lying awake at 3:00 AM thinking someone is, something is wrong with them, because now you can tell them maybe something is right. Until next time.