Waking Up at 3 A.M. Isn’t Always Insomnia

If you’ve ever woken up at 3 a.m., completely awake, you’ve probably done the math.

If I fall asleep right now, I’ll still get four hours.

A few minutes pass.

Three hours and fifty-five minutes.

Then comes the thought that somehow makes it even harder to fall back asleep:

What’s wrong with me?

It’s an understandable question. We’ve been taught to think of a “good” night’s sleep as eight uninterrupted hours. So when we wake in the middle of the night, it’s easy to assume something has gone wrong.

The research tells a more reassuring story.

Waking during the night isn’t always a sign that your sleep is broken or that you have insomnia. In many cases, it’s the result of two ordinary biological processes happening at the same time: a sleep pattern with deep historical roots and the natural rise of a hormone that helps prepare your body for wakefulness.

One has been disappearing for more than a century. The other is happening inside your body every morning, whether you notice it or not.

We Didn’t Always Sleep in One Block

For most of human history, a full night’s sleep wasn’t one uninterrupted stretch. The historian A. Roger Ekirch spent years combing through diaries, court records, and medical texts when he noticed something unexpected: thousands of ordinary references to a “first sleep” and a “second sleep,” separated by a period of quiet wakefulness.

This wasn’t unusual, and no one seemed particularly concerned by it. People used that time to pray, talk, have sex, tend the fire, or simply lie awake thinking. One 16th-century French physician even recommended the period after first sleep as the best time for couples to conceive. The Romans called it primus somnus, or “first sleep.” References to the same pattern appear in sources dating back to ancient Greece. A similar pattern also appears in the Islamic tradition. Muslims have long been encouraged to wake during the latter part of the night to pray tahajjud, a voluntary prayer offered before dawn that has been practiced for centuries. While this isn’t evidence for segmented sleep itself, it reflects a long-standing cultural and religious tradition that treated waking during the night as something meaningful rather than unusual.

The uninterrupted eight-hour night many of us think of as “normal” is, historically speaking, relatively new. Ekirch argues that as artificial lighting became more common, people stayed awake later into the evening. Over time, first sleep expanded, the wakeful period between sleeps became shorter, and eventually disappeared for many people.

Like any historical research, Ekirch’s conclusions have been debated. Some historians argue that later retellings have gone further than the evidence itself, turning “this pattern appeared frequently” into “this is how everyone naturally slept.” Those aren’t the same claim.

The evidence points to a narrower conclusion. Segmented sleep was clearly common for long periods of history. It wasn’t universal, and it doesn’t mean your body is supposed to wake every night. But it does remind us that waking in the middle of the night isn’t, by itself, evidence that something has gone wrong.

Your Hormones Are Already Preparing You to Wake

Your body isn’t idle while you’re asleep. Hours before you wake up, cortisol begins to rise. Although it’s often called “the stress hormone,” cortisol does much more than respond to stress. One of its everyday jobs is helping prepare your body to wake.

Sleep researchers call this the cortisol awakening response, or CAR. Cortisol typically rises by 38 to 75 percent during the first 30 to 45 minutes after waking, building on a slower increase that gets underway earlier in the morning. Researchers believe this rise helps mobilize energy, increase alertness, and prepare the brain for waking.

That increase typically gets underway in the early morning hours, commonly somewhere between 4 and 6 a.m. That timing overlaps with when many people report waking “for no reason.” Sometimes your body isn’t malfunctioning. It’s preparing for wakefulness a little earlier than you’d prefer.

Like most biological processes, this isn’t identical for everyone. The cortisol awakening response follows your circadian rhythm rather than a fixed clock time, and researchers are still studying exactly what triggers it. Chronic stress and conditions such as anxiety or depression can also alter this rhythm and genuinely disrupt sleep. If early waking becomes frequent, distressing, or is accompanied by persistent anxiety, it’s worth discussing with your doctor.

Parents of babies and young children often experience a different version of the same night. Their body’s natural wakefulness may overlap with a child calling out from the next room. For many parents, the biology and the interruption simply happen to arrive at the same time.

What Actually Changes When You Know This

None of this is a sleep hack. Understanding what’s happening won’t necessarily stop you from waking up. What it can change is what happens next.

For many people, the hardest part isn’t waking during the night. It’s everything that follows.

What’s wrong with me?

I’m never getting back to sleep.

Tomorrow is going to be awful.

Those thoughts make it harder to relax at the very moment your body is trying to settle back down. Knowing there’s both a historical and a biological explanation for what you’re experiencing doesn’t guarantee you’ll fall asleep faster. But it can interrupt that spiral before it gathers momentum.

Sleep researchers and clinicians consistently recommend a few simple strategies:

• Don’t check the time. It does nothing but hand your brain more material for math and worry.

• Keep the room dark and the activity quiet. If you’re comfortable, stay in bed and do something undemanding, the closest modern equivalent of what many people naturally did during those periods of wakefulness centuries ago.

• If you’re still awake after 10 to 15 minutes, get up for a short time. Keep the lights dim and choose something relaxing until you begin to feel sleepy again. Reading often works well, especially on paper or an e-ink device rather than a phone or tablet.

• Know when it’s time to ask for help. If early waking becomes frequent, leaves you exhausted during the day, or is accompanied by significant anxiety, it’s worth talking with your doctor. Historical context can be reassuring, but it isn’t a diagnosis.

A Different Way to Think About It

Our pre-industrial ancestors didn’t treat waking during the night as wasted time or a problem to solve. It was simply another part of the night. People prayed, reflected, tended the fire, or lay quietly with their thoughts before drifting back to sleep.

Modern life doesn’t really allow for a two-part night. Most of us can’t structure our lives that way anymore, and this isn’t an argument for trying to. But their perspective is still worth borrowing. They didn’t assume every period of wakefulness meant something had gone wrong.

The next time you wake at 3 a.m., you may still wish you were asleep. You may still feel frustrated. But you might be a little less likely to assume something has gone wrong.

Sometimes waking during the night is exactly what it feels like: an interruption. Other times, it’s the result of ordinary biological processes that have been part of human life for centuries. Knowing the difference won’t guarantee you’ll fall back asleep. It might simply help you worry a little less while you’re awake.

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If this resonated with you, I’d genuinely love to know what stayed with you most. Feel free to leave a comment or subscribe if you’d like future posts delivered to your inbox.

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References

Ekirch, A. R. (2001). Sleep We Have Lost: Pre-Industrial Slumber in the British Isles. The American Historical Review, 106(2), 343–386.

Ekirch, A. R. (2005). At Day's Close: Night in Times Past. W. W. Norton.

Further Reading

Stanley, J. (2023). Have We Lost Sleep? A Reconsideration of Segmented Sleep in Early Modern England. Cambridge Core.

Clow, A., Thorn, L., Evans, P., & Hucklebridge, F. (2010). The Cortisol Awakening Response: More Than a Measure of HPA Axis Function. Neuroscience & Biobehavioral Reviews.

Wilhelm, I., Born, J., Kudielka, B. M., Schlotz, W., & Wüst, S. (2007). Is the Cortisol Awakening Rise a Response to Awakening? Psychoneuroendocrinology.