Modern sleep advice is usually presented as the solution to a modern problem, but the most useful research on this topic comes from looking back. Comparing how humans slept before electricity, screens, and fixed working hours with our sleep today shows quite accurately which parts of modern life work against a biology that has never changed.
The two-part sleep pattern that historians have actually found
Historian Roger Ekirch’s research into pre-industrial European sleep records, court records, diaries, and medical texts spanning several centuries consistently found references to a "first sleep" and a "second sleep"—two distinct phases of sleep with an hour or more of quiet wakefulness in between, in the middle of the night. This segmented pattern was apparently the normal, unremarkable way of sleeping before artificial light extended the usable evening and pushed sleep into a single block. The waking period between the two segments was apparently used for quiet reflection, prayer, conversation, or intimacy, and was treated as a normal, expected part of the night, not as a sleep problem.
What sleep researchers found when they removed artificial light
A study led by sleep researcher Thomas Wehr exposed participants to conditions with exclusively natural light for several weeks. Their sleep spontaneously reorganized into a segmented pattern strikingly similar to the historical findings: two separate sleep phases with a period of quiet wakefulness in between. This suggests that the two-part pattern is not a historical curiosity, but a natural expression of human sleep biology as soon as artificial light no longer overrides it. Some researchers are therefore rethinking modern insomnia, especially nighttime waking that resolves on its own without anxiety, as potentially closer to an ancient normal state than a disorder.
The internal clock that early humans lived by without knowing it
Long before anyone understood the suprachiasmatic nucleus or melatonin, human sleep timing was controlled entirely by sunlight: waking at dawn, powering down at nightfall, guided by a light-dark contrast far more extreme than anything most people experience indoors today. This is the primordial state to which modern circadian research keeps returning: morning light is by far the strongest signal for the internal clock, and a large portion of modern sleep disorders stems from the discrepancy between the amount of light the system is built for and what indoor living actually provides.
Seasonal variation, another pattern that modern life has erased
Historical and anthropological research on pre-industrial and hunter-gatherer societies finds sleep durations that fluctuate significantly with the seasons—longer in winter, shorter in summer—following the changing length of natural darkness rather than a fixed annual value. Modern life, with its artificial light and fixed schedules, has largely leveled this fluctuation, and some researchers see this leveling as a possible contributor to the seasonal mood and energy fluctuations that many people experience without a clear explanation.
What this actually means for a routine today
None of this means recreating pre-industrial life. Most of what the old sleep patterns got right—movement in daylight, darkness that was truly dark, an environment free of artificial stimuli deep into the night—are the very foundations that modern sleep science keeps rediscovering under new names. This is the logic behind the LongevityLife routine: building it around the same two anchor points that structured our ancestors' sleep: morning light, paired with NMN at the same time to support the body's own NAD+ production cycle exactly at its natural peak, and a truly dark, undisturbed night, supported by nasal strips for the one variable—restricted nasal breathing—that early humans dealt with just as we do today.
The honest conclusion
Early human sleep wasn't better because it was old. It was often better aligned with the biology that controls the system to this day, simply because there was nothing yet that could override it. The most useful lesson from this research is not nostalgia for pre-industrial life. It is the reminder that light, darkness, and airways counted for exactly the same physiological reasons then as they do now, and that a modern routine which truly respects these mechanisms is closer to what the body was built for than most of what passes for a normal night today.