Before electricity, humans slept twice a night; scientists explain why biphasic sleep made perfect sense

Before electricity and endless screen time took over, humans followed a very different rest routine. In the pre-industrial world, people didn’t sleep in one uninterrupted stretch but in two distinct phases known as first sleep and second sleep.

Between these two rests, they often stayed awake for an hour or two, praying, reading, or quietly reflecting. This older form of biphasic sleep was not a sign of insomnia but a natural way of living that matched the body’s rhythm before modern life reshaped our nights.A peer-reviewed study in the Journal of Sleep Research (2018) found that exposure to artificial light disrupts the circadian rhythm by delaying melatonin secretion, the hormone that regulates sleep cycles.

Researchers concluded that electric lighting and evening activities were major factors behind the disappearance of segmented sleep in industrialised societies.

What is biphasic sleep, and why is it suited to our natural rhythm

Biphasic sleep, also known as segmented sleep, was the typical pattern for centuries across Europe, Africa and parts of Asia. People would go to bed shortly after sunset, sleep for about four hours, wake up around midnight for quiet activities, and then return to bed for their second sleep.

During this in-between period, people might tend to the fire, talk, write, meditate, or even visit neighbours. Far from being considered restless or unhealthy, this night-time wakefulness was seen as peaceful and restorative, a natural pause between two halves of rest.

How melatonin and circadian rhythm influenced early sleep patterns

Before electricity, human sleep patterns were deeply synchronised with the sun’s rise and fall. The circadian rhythm, our internal biological clock, follows the natural light-dark cycle, allowing melatonin to be released soon after dusk.

This hormone signalled the body to wind down, making early sleep feel natural.When artificial light and late-night work became common, this delicate cycle shifted. Studies show that exposure to bright lights in the evening suppresses melatonin production, keeping people awake longer. As bedtime moved later, the natural window for first sleep disappeared, merging both sleep segments into the single, continuous stretch we know today.

The historical evidence behind segmented sleep patterns

Historical records, court transcripts and personal diaries from the 15th to 18th centuries reveal that segmented sleep was an accepted routine. Historian Roger Ekirch’s research uncovered hundreds of references to first sleep and second sleep, proving it was not limited to one culture.This middle-of-the-night interval was often used for relaxation, reflection, and even creative thinking. People valued the silence and calm darkness, treating the period between sleeps as time for spiritual or personal reflection.

Unlike today, waking up at 2 a.m. wasn’t a cause for alarm, it was a familiar and even cherished part of life.

How industrialisation ended biphasic sleep

The Industrial Revolution changed everything. With factories, gas lamps, and later, electric lights illuminating city streets, people stayed awake longer. Work schedules demanded consistent hours, forcing society to compress rest into one continuous block.As artificial light delayed the body’s melatonin release, natural cues for sleep weakened.

Modern stress, caffeine, and irregular routines further disrupted the circadian rhythm. Within a century, the biphasic sleep pattern that had defined humanity for millennia nearly vanished, replaced by the modern monophasic sleep cycle.

Why waking up at night may be completely normal

If you often wake up in the middle of the night, you’re not necessarily struggling with insomnia; it might be your body echoing ancient sleep rhythms. Sleep scientists explain that brief periods of wakefulness between sleep cycles are natural.

What’s changed is how we interpret them.In the past, people saw night-time wakefulness as an opportunity for reflection or rest. Today, we panic about it, turning a normal biological rhythm into anxiety-driven insomnia. Understanding this connection between segmented sleep and circadian rhythms can help normalise such awakenings and reduce unnecessary sleep stress.

Could biphasic sleep make a modern comeback

Some people are revisiting biphasic sleep to match flexible work hours or natural energy patterns.

They find that dividing sleep into two sessions, one longer at night and a short nap or second rest, can enhance focus and alertness.While results vary, small studies suggest that allowing the body to follow its natural cycles improves mood and cognitive function. Still, most sleep experts recommend consistency: a regular sleep-wake schedule supports melatonin balance better than fragmented rest.Our ancestors’ segmented sleep patterns reflected a slower, more organic lifestyle in sync with nature.

Modern life compressed those rhythms into a single block, making us forget the body’s natural ebb and flow. But traces of biphasic tendencies remain, in brief night awakenings, early-morning calm, and the drowsiness that hits mid-afternoon.Reconnecting with these patterns doesn’t mean abandoning modern schedules. It means understanding that sleep is adaptable, not one-size-fits-all. Whether you rest once or twice a night, the key lies in respecting your circadian rhythm and creating an environment that supports it. True rest, after all, comes not from the number of hours you sleep, but from how closely your body aligns with its natural rhythm.Also read| Male vs female black widow spiders: How to tell them apart and why females dominate