Why 8 Hours of Sleep Might Be the Wrong Goal Entirely
I have spent more nights than I can count staring at the ceiling at 3 in the morning, wide awake, doing the math on how many hours of sleep I had left before my alarm went off. Then doing the math again an hour later. Then feeling the familiar dread that tomorrow was already ruined before it started.
If you've been there, I want to tell you something that took me a long time to learn. The version of sleep we've been chasing, eight uninterrupted hours, lights out and gone until morning, might not be the natural human pattern at all. And understanding that changed how I think about my own nights completely.
What Actually Happens During Sleep
Before we get to the bigger question, it helps to understand the basic architecture of a night's sleep. Your body moves through cycles of two main types of sleep: REM and non-REM. Non-REM sleep itself has three stages, the deepest of which, stage three, is when your body does its physical repair work, rebuilding tissue, strengthening the immune system, and restoring the body. REM sleep is when most dreaming happens and where memory processing takes place.
Each full cycle through these stages takes roughly 90 minutes, and a typical night involves four to six of these cycles. As the night progresses, the proportion shifts. Early cycles contain more deep sleep. Later cycles, especially in the final third of the night, contain longer stretches of REM.
This matters because it means sleep isn't one continuous flat experience. It's a rhythm with natural transitions, and at the end of each 90 minute cycle, brief arousals toward lighter sleep or even brief wakefulness are completely normal. Most people don't remember these moments. Some of us, especially as we get older or move through hormonal transitions, remember them very well.
Where the 8 Hour Rule Actually Came From
The 8 hour figure isn't wrong, exactly, but it's often misunderstood. Most sleep researchers and bodies like the CDC recommend 7 or more hours for adults, with a healthy range generally falling between 7 and 9 depending on the individual. That's a real, evidence based recommendation for total sleep needed.
What gets lost is the assumption that those hours need to happen in one unbroken block, and that any deviation from that means something is wrong with you. That assumption has a much shakier foundation than most people realize.
What Sleep Looked Like Before Electric Light
Historian Roger Ekirch spent years researching sleep patterns in preindustrial Europe through diaries, court records, and medical texts. What he found was a pattern almost nobody talks about today. From the 16th through 18th centuries, segmented sleep, two distinct sleep periods separated by roughly an hour of quiet wakefulness in the middle of the night, was described as completely normal. People referred to their "first sleep" and "second sleep" as an ordinary part of life. During the waking interval, people prayed, talked, had sex, or simply rested by the fire before returning to sleep until morning.
This wasn't isolated to Europe. Similar patterns showed up in written accounts from other preindustrial cultures around the world, all sharing one thing in common: the absence of artificial light extending the day.
A study from the National Institute of Mental Health in the early 1990s tested this directly. When researchers placed modern subjects in conditions of extended darkness, roughly 14 hours a night, mimicking a preindustrial winter night, their sleep spontaneously reorganized into two distinct bouts, separated by a period of quiet wakefulness, very similar to what Ekirch found in the historical record.
What Modern Hunter-Gatherer Studies Show
Here's where it gets more complicated, and more honest.
Researcher Jerome Siegel led a major study examining sleep in three present day hunter-gatherer societies, the Hadza in Tanzania, the San in Namibia, and the Tsimane in Bolivia, none of whom have access to electric light. Across more than a thousand combined days of data, all three groups showed a strikingly similar pattern: they slept for roughly 5.7 to 7.1 continuous hours each night, generally in a single block, not segmented into two periods.
Notably, they didn't go to sleep right at sunset. They stayed up for several hours afterward, tending fires, talking, preparing for the next day, then slept through most of the night and woke before sunrise. And contrary to what you might expect, these groups reported very little insomnia. Sleep complaints, so common in industrialized societies, were largely absent.
So which is it, segmented sleep or one consolidated block? The honest answer is that human sleep appears to be genuinely flexible, shaped heavily by light exposure, temperature, and season. Researchers studying hunter-gatherer sleep have also found that sleep duration shifts notably across seasons, with people sleeping roughly an hour longer in colder months than in warmer ones, suggesting temperature plays as large a role as light in regulating natural sleep timing.
What stays consistent across both the historical and modern hunter-gatherer research is this: humans were never sleeping a perfectly flat, uninterrupted eight hours on a rigid schedule every single night, and brief wakefulness during the night was never treated as a problem to fix.
One More Piece: We May Never Have Slept Entirely Alone
There's a theory worth mentioning here, called the sentinel hypothesis, the idea that humans evolved to sleep in groups specifically because having some members of the group awake at any given time provided protection. A study of the Hadza found that across 20 days of observation, almost the entire night included at least one person from the group awake at any given moment, even though everyone individually slept a normal amount. Sleep, in other words, may have always been something experienced collectively and asynchronously, not as one synchronized block where an entire group lost consciousness at the same time.
That reframes nighttime wakefulness as something closer to a feature of human sleep than a flaw in it.
Why You Might Be Waking at 3am Specifically
This is the part that mattered most to me personally, because my own wake-ups were rarely random. They happened at almost the same time most nights.
Cortisol follows its own daily rhythm, dropping to its lowest point around midnight and then beginning a slow rise in the early morning hours before peaking shortly after you wake, which is part of what gets you out of bed and alert. In people under chronic stress or with disrupted sleep patterns, research has found that this rise can happen earlier and more steeply than it should, which lines up closely with the common experience of waking abruptly between 2 and 4am, wide awake, heart slightly elevated, unable to drift back off easily.
This creates a frustrating loop. Elevated cortisol disrupts sleep, and disrupted sleep itself raises cortisol the following day, each one feeding the other.
For women specifically, this gets layered with another mechanism. Progesterone has a direct calming effect on the brain, acting on the same receptors as anti-anxiety medications. As progesterone declines during perimenopause, that calming effect weakens, which research has tied directly to more nighttime awakenings and lighter, less restorative sleep. This is well documented in the research on perimenopausal sleep disturbance and is one of the more underexplained pieces of the entire transition.
What Helped Me, and What the Research Actually Supports
I want to be honest that I haven't solved this perfectly. But understanding the mechanism changed my relationship to those nights considerably, and a few specific things made a real difference.
Morning light exposure mattered more than I expected. The hunter-gatherer research found their sleep was tightly tied to natural light and darkness, and getting outside within the first hour of waking helps anchor your circadian rhythm and the cortisol curve that governs it.
Going to bed earlier, closer to the pattern the hunter-gatherer studies described of sleeping shortly after dark rather than staying up late under artificial light, made a measurable difference for me. Research has consistently found that sleep occurring earlier in the night tends to include more of the deep, restorative stages.
Not panicking at 3am was, oddly, one of the most useful changes. Once I understood that brief nighttime wakefulness has likely always been a normal part of human sleep, the anxiety of being awake stopped compounding the problem. The dread itself was raising my cortisol further and making it harder to fall back asleep.
And stabilizing my blood sugar before bed helped more than almost anything else. A blood sugar drop overnight is itself a stress signal that prompts a cortisol and adrenaline response, which can be enough to wake you outright. Eating a dinner with adequate protein and fat, rather than a carbohydrate heavy meal that spikes and then crashes blood sugar overnight, reduced how often I woke abruptly.
None of this gave me a perfect, uninterrupted eight hours every night. What it gave me was a calmer relationship with the nights that weren't perfect, and noticeably better sleep on the nights that were.
If you've spent years feeling like a failure every time you wake at 3am, I want you to know the research suggests you might be experiencing something much closer to ordinary human sleep than you've been told.
This article is for educational purposes only and does not constitute medical advice. If sleep difficulties are significantly affecting your quality of life, please consult a qualified healthcare provider.
References:
Ekirch AR. Segmented sleep in preindustrial societies. Sleep. 2016;39(3):715-716. https://pmc.ncbi.nlm.nih.gov/articles/PMC4763365/
Yetish G, et al. Natural sleep and its seasonal variations in three pre-industrial societies. Curr Biol. 2015;25(21):2862-2868. https://www.cell.com/fulltext/S0960-9822(15)01157-4
Samson DR, et al. Sound reasons for unsound sleep: comparative support for the sentinel hypothesis in industrial and nonindustrial groups. Am J Hum Biol. 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10024786/
Abell JG, et al. Recurrent short sleep, chronic insomnia symptoms and salivary cortisol: a 10-year follow-up in the Whitehall II study. Psychoneuroendocrinology. 2016;68:91-99. https://pubmed.ncbi.nlm.nih.gov/26963369/
Baker FC, et al. Sleep disturbance and perimenopause: a narrative review. Climacteric. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC11901009/
Caufriez A, et al. Progesterone prevents sleep disturbances and modulates GH, TSH, and melatonin secretion in postmenopausal women. J Clin Endocrinol Metab. 2011;96(4):E614-E623. https://pubmed.ncbi.nlm.nih.gov/21270329/
