The Anxiety of Not Knowing

I spent four months convinced something was seriously wrong with me.

Not "I should probably see a doctor" wrong. More like "I'm googling (or whatever we call asking AI now) symptoms between meetings and scaring myself" wrong. Heart racing for no reason. A low-grade dread that showed up mid-afternoon and just... sat there. Irritability that felt disproportionate to everything. I'd snap at someone over nothing, then feel terrible about it, then feel anxious about feeling terrible. A loop with no exit.

The symptoms were bad. But what was worse, much worse, was not having a name for any of it.

When your body stops making sense

I'm someone who likes to understand things. Give me a problem and I'll research it, find the pattern, figure out the approach. That's how I'm wired. But for those four months, my body was doing things I couldn't explain and couldn't predict. The anxiety would appear on a Tuesday for no reason and be gone by Thursday. My mood would crater for three days, then lift like nothing happened. My resting heart rate would jump 8 beats overnight and I'd spend the whole next day wondering if something was wrong with my heart.

My wearable told me I was stressed. My doctor said the same. And when I pushed back ("but stressed about what?"), I got the gentle suggestion that maybe I wasn't aware of my own stress levels.

That's a particular kind of frustrating. Being told the answer is stress when you know the question is bigger than that.

The numbers behind the mood shift

When I finally found the research, the first thing that hit me was scale.

Freeman and colleagues (2006) found that women moving through perimenopause were about 2.5 times as likely to have a first-time episode of depression as women who had not yet started the transition. A first time. In women with no prior history. Within that same research, the association ran higher in some groups. Roughly 5 times as likely in women with a history of strong premenstrual mood shifts, about 4 times with a history of past low mood, and about 3 times with poor sleep. Whether these patterns hold for women with PCOS is, characteristically, unstudied.

A 2024 review by Fang and colleagues pooled hundreds of studies covering nearly half a million women. It found that more than half reported anxiety during and around the menopausal transition. More than half. It also found low mood in 43% and irritability in 54%. Longer-term data from the SWAN study (Bromberger and colleagues, 2013) found this rise held up even after accounting for life stress, general health, and hot flashes.

Over half of us are dealing with this. And I'd never heard a single number.

Cunningham and colleagues (2025) found that psychological symptoms tend to peak in the early 40s, during early perimenopause. The physical symptoms most people link to menopause, hot flashes and night sweats, tend to peak in the early 50s.

So the mood hits first. Often years before the symptoms most people associate with menopause. Which means you're anxious and irritable and don't even have the obvious markers to point to. You just feel wrong.

That is me in my 40s. Mood symptoms without a clear cause. And no context to put them in.

It's not "just stress." It's chemistry.

The mechanism, once I found it, was clarifying in a way I didn't expect.

Estrogen doesn't just manage reproduction. It also helps regulate serotonin, a brain chemical tied to mood and emotional stability. When estrogen fluctuates during perimenopause, serotonin can shift with it. That is not a metaphor. It is chemistry.

Bromberger et al. (2015), using SWAN data: mood symptoms correlate more with estrogen variability than with absolute levels. Rapid fluctuations (more than 50 pg/mL change in two weeks, if you want the number) predicted mood instability more reliably than low estrogen alone.

Your brain can adapt to a new baseline. What it can't easily adapt to is the ground shifting every few days.

Then there's progesterone. GABA is your brain's main calming neurotransmitter. The thing that says "it's fine, settle down." Progesterone supports GABA function. When progesterone drops (which happens irregularly and unpredictably during perimenopause), you lose that calming signal. The result feels exactly like what it is: anxiety without a reason. Your brain's calming system is intermittently going offline, and nobody told you.

Knowing that didn't fix it. But it changed what I was dealing with. It went from "I'm becoming an anxious person" to "my neurochemistry is doing something predictable, even if it doesn't feel predictable yet."

The body keeps a different score

Here's what connected the dots for me. The mood symptoms weren't happening in isolation. They were connected to everything else.

There is a well-documented link between low mood and heart-rate variability. In research on depression, such as Kemp and colleagues (2010), people with depression tended to have lower heart-rate variability, a moderate difference of about -0.46 on the researchers' scale (the minus sign just means the two move in opposite directions). Lower variability may go together with less recovery capacity, which can feed into worse sleep and, in turn, lower mood. The loop can reinforce itself.

I could see this in my own data once I knew what to look for. The weeks where my mood was worst weren't random. They aligned with my luteal phase. They coincided with higher resting heart rate, lower HRV, and worse sleep efficiency. Three separate metrics, all moving together, all pointing to the same hormonal shift.

Before I saw the pattern, those were just bad weeks. After I saw it, they were predictable bad weeks. And that distinction matters more than it should.

The cost of not knowing

I want to be careful here because I'm not a therapist and this isn't medical advice. But I want to say something that I think is true and that nobody said to me during those four months.

Unexplained symptoms are worse than explained ones.

When you don't know why you're anxious, the anxiety becomes self-referential. You're anxious about being anxious. You start questioning your own perception. Am I overreacting? Is this normal? Am I the kind of person who can't handle things? That internal interrogation is exhausting. And it happens on top of whatever the original symptom was.

When you find out that over half of women in your situation experience anxiety, that the neurochemical mechanism is well-documented, that your mood correlates with measurable physiological shifts... the symptom doesn't disappear. But the second layer does. The "what's wrong with me" layer. The layer that makes you feel alone in it.

Low mood and anxiety often show up together during this transition. In Fang and colleagues' 2024 review, more than half of women reported anxiety and 43% reported low mood, so the overlap is common. If some of that sounds familiar, it does not mean you are fragile. It may mean your body is moving through a well-documented hormonal transition that a large share of women go through. The numbers don't make it easier, but they can make it feel less lonely.

What changed for me

Three things, in order of impact.

Seeing the pattern. Once I could track my mood alongside my cycle, my sleep, and my HRV, I could see the rhythm. Bad weeks had a shape. They started in the same phase, lasted the same duration, and resolved the same way. That didn't make them good weeks. But it meant I could stop bracing for the unknown and start preparing for the known.

Telling my doctor what I actually found. "I'm feeling anxious" is hard to act on. "My anxiety clusters in my late luteal phase, coincides with a 25% HRV drop and sleep efficiency below 78%, and resolves within 3-4 days" is a different conversation entirely. My doctor's response changed. The conversation got specific. Options appeared.

Stopping the self-blame. This was the biggest one and the hardest to describe. For months, every bad mood felt like a personal failure. Like I should be handling it better. Like the anxiety meant something about who I was becoming. Understanding the physiology didn't eliminate the symptoms. But it eliminated the guilt. And guilt, it turns out, was taking up a lot of space.

Why this matters beyond me

Millions of women in North America are in perimenopause right now. More than half report anxiety. The majority haven't been told that their mood symptoms have a physiological basis that peaks years before the symptoms they'd recognize as menopause.

That gap. Between what's happening in your body and what anyone has explained to you about it. That's where the worst damage happens. Not from the hormones themselves, but from the months or years of wondering what's wrong. Of being told it's stress. Of half-believing that maybe you're just not coping well enough.

You're coping fine. Your serotonin is likely fluctuating. Your progesterone may be dropping in fits and starts. Your brain's calming system is dealing with a supply-chain problem.

Once you know that, something shifts. Not everything. But something important.