Modern sleep advice is usually presented as a solution to a modern problem, but the most useful research on the subject comes from looking back. Comparing how people 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 Bimodal Sleep Pattern Historians 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 separate sleep phases 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 to sleep before artificial light extended the usable evening and compressed sleep into a single block. The waking phase 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 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 only 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 bimodal pattern is not a historical curiosity but a natural expression of human sleep biology, once artificial light no longer overrides it. Some researchers are therefore rethinking modern insomnia, especially nocturnal awakenings that resolve themselves without anxiety, as possibly closer to an ancient normal state than a disorder.
The Internal Clock Early Humans Lived By, Without Knowing It
Long before anyone understood the suprachiasmatic nucleus or melatonin, human sleep timing was entirely controlled by sunlight: waking with dawn, winding down with dusk, guided by a light-dark contrast that was far more extreme than anything most people experience indoors today. This is the primal state to which modern circadian research repeatedly returns: morning light is by far the strongest signal for the internal clock, and a large part of modern sleep disturbances can be traced back to the discrepancy between the amount of light the system is built for and what an indoor life actually provides.
Seasonal Fluctuation, Another Pattern Modern Life Has Erased
Historical and anthropological research on pre-industrial and hunter-gatherer societies finds sleep durations that vary 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 artificial light and fixed schedules has largely flattened this fluctuation, and some researchers see this flattening as a possible contributor to the seasonal mood and energy fluctuations that many people experience without clear explanation.
What This Actually Means for a Modern Routine
None of this means recreating pre-industrial life. Most of what ancient sleep patterns got right—daylight movement, darkness that was truly dark, an environment free of artificial stimuli late into the night—are precisely the fundamentals that modern sleep science continually rediscovers under new names. This is the logic behind building the LongevityLife routine around the same two anchor points that also structured our ancestors' sleep: morning light, paired with NMN at the same time to support the body's natural NAD+ production cycle precisely at its natural peak, and a truly dark, undisturbed night, supported by the nasal strip for the one variable, restricted nasal breathing, that early humans dealt with just as much as we do today.
The Honest Conclusion
The sleep of early humans was not better because it was ancient. It was often better attuned to the biology that still governs the system today, simply because there was nothing yet to 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 mattered then for the exact same physiological reasons as they do today, and that a modern routine that truly respects these mechanisms is closer to what the body was built for than most of what passes for a normal night today.