For years, the gold standard sleep question has been: Are you getting 7–9 hours? For many women, though, even if we clock a “full night,” we still face the 2 to 4 a.m. witching hour, or multiple wake-ups, and wonder whether it actually counts as restorative sleep.

The physiology of true sleep fragmentation does have consequences, but brief wakefulness throughout the sleep cycle is natural. How you respond to those wakings may shape your body’s ability to recover overnight though. Increasingly, researchers say the better question isn’t how long you sleep — but how continuous that sleep is.

😴 Ever wonder what happens when women don’t sleep enough? Science shows women pay a steeper price for poor sleep in multiple ways. Read more here.

This is the bigger question for women right now: How do we use data without becoming ruled by it? Because sleep efficiency, glucose curves, DEXA scans — they’re only powerful if you know how to interpret them.

This tension between data and discernment is something we’re exploring more deeply at the Livelong Women’s Health Summit. At the Summit, physicians and scientists like Kayla Barnes, Dr. Nicki Bryne, and Heidi Davis are unpacking how women can use health data wisely without turning it into another stressor.

If you’re curious how to work with your biology instead of against it, this is the room you want to be in.

💸Use the code TIFFANY to get $50 off any ticket type.

Major Allison Brager, Ph.D., a neuroscientist with expertise in sleep and circadian rhythms, says brief periods of wakefulness throughout the night are normal. The natural course of the 90-minute sleep cycle moves from non-REM to REM to brief wakefulness, she says. That’s part of being human.

The concern is when wake-ups become longer, more frequent, or harder to recover from. That’s when sleep becomes clinically fragmented.

Clinically fragmented sleep refers to repeated interruptions that prevent you from staying in deeper stages long enough to complete the sleep cycle. Think of the wakings that happen with sleep apnea as an example. Or, if you wake up in the middle of the night and have greater than 15-20 minutes of wakefulness where you cannot get back to sleep, that would also be considered an issue, says Brager. 

💡 If that wake-up happens between 2 and 4 a.m., it can feel especially destabilizing. That’s because this window often overlaps with your lowest core body temperature and a REM-rich portion of the night, says Brager.

Brager says this is why the most useful number to measure isn’t total sleep time. Instead, it’s sleep efficiency — how much of your time in bed is time asleep. “Being in bed for five hours and having 98% sleep efficiency is better than being in bed for eight hours and having 40% sleep efficiency,” she adds.

Research increasingly shows that poorer sleep efficiency and higher wake-after-sleep-onset (often called WASO and means, essentially, how long you’re awake after first falling asleep) are linked to markers of cardiometabolic risk, autonomic stress, and mood instability.

Brager’s general rule of thumb:

✅ 92%+ efficiency is ideal

🚨 Below 85% is concerning

This aligns with how sleep researchers interpret actigraphy data (the way they measure your activity and movements): uninterrupted sleep often predicts next-day function better than raw duration of sleep.

As with most health data, trends matter more than a single night’s number.

Women are often told they need more sleep than men. But the story is more nuanced, and it isn’t a new discovery.

Decades ago, researchers Rachel Manber (Stanford) and Terri Lee (Yale) documented sex differences in sleep initiation and maintenance across the lifespan. Their work received little mainstream attention, but wearables are now making those differences visible.

Hormonal shifts across the menstrual cycle, pregnancy, and perimenopause can alter thermoregulation and REM density — both of which influence middle-of-the-night awakenings. And modern stress, light exposure at night, thermoregulatory shifts (hello, perimenopause), and a hypervigilant nervous system can destabilize the middle of the night for many women. 

So what can women actually do about this without turning sleep into a second job?

The goal isn’t perfection. It’s protecting continuity. As with most health or longevity-related things, the emphasis is on the basics. Brager recommends a few things in particular:

The goal is to reduce the things that keep your nervous system activated in the first place. And quite often, small adjustments protect your ability to stay asleep better than elaborate nighttime rituals.

It may be that we’ve been asking the wrong question.

🚫 It’s not: How many hours did I sleep? 

💡 But: Did my body get uninterrupted recovery time?

Sleep is your body’s primary metabolic recovery window. If we can treat night waking as the signal it is, we can work toward diagnosing a root cause and addressing what we discover. No elaborate nighttime routine required.

The Livelong Women’s Circle is where topics like this go deeper — real conversations about sleep, stress, midlife changes, heart health, prevention, and what actually works as we age.

If you’re looking for a smart, supportive space to ask questions and learn alongside other women who care about long-term health, you’re welcome here.

👉 Join the Livelong Women’s Circle

We asked, you answered!

Which feels closest to your experience right now?

The answers were pretty evenly split, but “My sexual activity has declined alongside stress, sleep, or hormonal changes” was slightly ahead. If you have questions about any of these topics we haven’t dug into yet, I’d love to know. You can always email me at [email protected] to start a conversation. 😊

Curious about your health? Liv will search everything we’ve published to help you find the answer. Chat with her here.

Women’s sleep (and women’s physiology more broadly) has been understudied for decades. If you care about prevention and elevating better conversations, we’d love to have you join us as a Livelong Ambassador for the Livelong Women’s Health Summit.

👉 Apply here

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