So, Is It Your Hormones?

In plain words

Your brain isn’t separate from the rest of your hormone system.

Imagine someone told you that a chemical in your body had changed. You’d probably expect something obvious to happen next. The trouble is that your brain doesn’t work like a row of light switches.

Hormones work through receptors. A receptor is a bit like a lock that only certain keys fit, and your brain has receptors for hormones in lots of different areas. Take estrogen, which is usually described as a reproductive hormone. Its main form during the reproductive years is called estradiol. Estradiol can affect several of the brain’s own chemical messengers, including serotonin and dopamine. Those play a part in mood, motivation, learning, memory and reward. That’s a lot of territory for one hormone to touch!

So yes, hormones can affect how you feel and think. What a hormone does depends on a lot, though: which hormone it is, which receptor it meets, where that happens, the timing, and what else is going on in your body and your life at the same time.

Much of the research on how estradiol works in the brain comes from animal and lab studies. There’s a long way between “estradiol interacts with serotonin,” which is a statement about biology, and “estrogen is why you feel sad today,” which is usually a guess. Human behavior is not a hormone chart.

In plain words

How much of a hormone you have and what it does to you are two different things.

Say a few people go through the same hormonal change. One notices very little. Another gets more irritable or anxious. Someone else mostly notices their sleep changing. Another notices nothing at all, until they look back over a few months and realize there’s a pattern.

That stops being mysterious once you stop thinking of hormones as instructions. Hormones are signals, and every brain reads them a little differently.

Lots of things shape how a brain reads them: your history, other hormones, stress, sleep, genes and how fast a hormone changes.

One of the clearest examples is PMDD, short for premenstrual dysphoric disorder. It means mood symptoms, like irritability, low mood, anxiety and quick mood swings, that come back in the same part of most cycles. That part is the second half, from ovulation to your next period, when progesterone rises. It’s called the luteal phase, and the first half is the follicular phase.

People with PMDD don’t seem to have unusual hormone levels. Research more and more points to a brain that reacts more strongly to perfectly normal hormonal ups and downs. If ordinary hormonal ups and downs were bad for mood in themselves, most people would have strong emotional reactions to them every month. Most people don’t.

In plain words

Online, you’ll read that each phase of your cycle is good for something different, like being productive one week and confident the next. It’s an appealing story. It’s also much neater than the evidence.

A big recent review pulled together more than a hundred studies of attention, planning, creativity, intelligence and more. It found no reliable evidence that your cycle changes how well your brain actually performs.

You don’t become less intelligent because your period is coming. There’s no good evidence that your thinking switches off on Thursday and comes back about three days later. Fortunately. It would make scheduling meetings considerably more complicated.

A test can show no change in how well you perform while you still feel different. That doesn’t mean you’re imagining what you notice. How you do on a test is only one part of how your day actually feels.

You can sleep badly, be in more pain or feel more emotional without your thinking getting worse. You can be exhausted and still do fine on a memory test in a lab, while feeling, quite sincerely, that your brain has been replaced by damp cardboard.

“Brain fog” can mean lots of things, like forgetting words, struggling to focus, sleeping badly, worrying or being worn out, sometimes all at once. A standard thinking test only picks up some of that.

This comes up a lot around menopause. Many people say their thinking has changed, while tests of memory and attention don’t always show it in the same way. Another recent review found that how people rate their own thinking and how they score on tests don’t line up neatly in the years around menopause. That’s not a reason to dismiss what people feel. Quite the opposite! “Thinking” is not one thing, and a test only measures part of it.

What the research does back up is that hormonal ups and downs come along with changes in sleep, pain, energy and how you feel. Those are two different claims, and it’s the second one the research supports.

In plain words

Progesterone is a hormone that rises in the second half of the cycle. People often call it the “calming” hormone, and that’s far too simple.

Your body turns some progesterone into other substances that act on the brain. One of them has a real mouthful of a name, allopregnanolone. It acts on receptors for GABA, part of one of the brain’s main braking systems, which generally calms nerve cells down. Allopregnanolone can boost that braking, which is why researchers study it in anxiety, stress, sleep and mood.

And this is where things get wonderfully inconvenient. Something that can have a calming effect doesn’t make everyone feel calm. In some people, changes in allopregnanolone go along with anxiety, irritability and low mood. Research on PMDD suggests that in people with the condition, the brain may respond differently as allopregnanolone rises and falls, and that this may help explain their symptoms.

In plain words

Sometimes “hormonal” and “psychological” are describing the same system from different directions. Your hormones and your stress system are connected, and they affect each other.

Say you’ve slept badly for three nights. You’re already on edge, and then someone loads the dishwasher “wrong” and you’re furious. Nothing about the dishwasher changed. The state you were in did, and hormones can be one part of that.

There’s some evidence that your stress response changes a little across the cycle. Cortisol is a hormone your body releases as part of that response, and one review found it rose slightly more after sudden stress in the second half of the cycle than in the first. The differences were small, and there isn’t much research yet. So it would be far too simple to say you’re more stressed before your period because your cortisol is higher. The researchers themselves say better studies are needed, and people differ a lot.

But the bigger idea matters. Your stress system doesn’t work on its own, and neither do your reproductive hormones. Neither works separately from your sleep, your immune system, your metabolism, pain, or the sense your brain is making of what’s happening. That’s why splitting experience neatly into “physical” and “psychological” can be misleading.

The loop below shows how a hormone change, sleep and stress can each lead to the next. You can start it anywhere.

So which part caused the feeling? There may not be one single answer.

Picture two people going through the same hormonal changes before their period. One is sleeping well and feeling fine. The other is sleeping four hours a night, is already anxious, lives with long-term pain and is dealing with a hard situation at work. It would be strange to expect them to feel the same. Hormones aren’t landing on an empty brain. They’re arriving in a system that’s already busy.

Hormones change the conditions your brain is working in. They don’t write the whole experience themselves.

In plain words

Puberty, pregnancy, the months after birth and perimenopause all bring big hormonal changes in a fairly short time, and the link between hormones and how you feel can become much easier to notice. They’re about more than hormone levels, though.

Perimenopause is the years leading up to your final period and the year after it, when cycles get irregular and hormone levels go up and down. Menopause itself is confirmed once twelve months have passed since your last period.

During pregnancy, hormones rise to very high levels. After birth, they fall dramatically, and fast. It’s tempting to blame postpartum depression, the depression some people have after having a baby, on that drop alone. But a recent review describes several things acting together: hormones, the stress system, the brain’s chemical messengers and the immune system, rather than a drop in hormones alone.

Then there’s everything else: lack of sleep, pain, recovering from the birth, changes in how you see yourself, feeding difficulties, your mental health history and how much support you have. And the extraordinary experience of suddenly being responsible for a person who has absolutely no respect for your preferred sleep schedule.

The hormones matter. They’re just not the whole story. A biological explanation should never erase the psychological and social ones. If you’re struggling after having a baby, it isn’t a failure of willpower or of love, and it’s worth telling your doctor or midwife.

Perimenopause is when many people first meet the phrase “brain fog.” It sounds vague until it happens to you. You walk into a room and forget why. A familiar word refuses to arrive. You can still do the work. You just feel less quick while you’re doing it.

And unlike the bigger claims about the menstrual cycle, this one has growing evidence behind it. The menopausal transition can bring real changes in how your thinking feels. A recent review of more than twenty studies found that people in perimenopause scored lower on thinking tests than people who hadn’t reached it yet. The result depended a lot on how the researchers decided who was in which stage. How people rated their own thinking and how they scored didn’t always match, either.

Sleep matters a lot here. Sleep problems are common around menopause, and hormone changes, hot flashes, night sweats and other things can all play a part. Poor sleep, in turn, can affect attention, memory, mood and how you handle your emotions.

So hormone changes may be affecting your concentration directly. They may also be disturbing your sleep, which can then affect attention and mood. And worrying about feeling less sharp can add another layer on top. Your brain doesn’t label each cause separately. It simply experiences the result.

In plain words

Sometimes. But that answer is much less useful than it sounds.

Hormones do affect how your brain works, including your mood, thinking, stress and sleep, and there’s good evidence for that. There’s also good evidence that hormonal changes can affect people very differently. That’s where “it’s just your hormones” starts to fall apart, because “your hormones” aren’t an explanation on their own. They’re one biological system working with others, and all of it works together with your history, your surroundings, your sleep, your relationships, your stress and your health.

Sometimes the hormonal part is clear, as with PMDD, where the hormone changes themselves are ordinary but the brain’s response to them can be very different. Sometimes it’s much harder to untangle, like brain fog in perimenopause, which can involve hormone changes, broken sleep, hot flashes, mood and stress all at once. And sometimes the answer really isn’t hormones. You may be exhausted because you’re exhausted. You may be irritable because somebody has been annoying you for three weeks and your nervous system has finally filed the appropriate paperwork. A hormonal explanation should add information. It should not replace curiosity.

Be careful with hormone explanations online. Hormones are invisible, powerful and complicated enough to sound convincing, which makes them perfect for internet certainty. But sounding biologically plausible is not the same as being proven.

Estradiol has lots of effects on the brain, but that doesn’t mean taking estrogen will automatically lift your mood or sharpen your thinking. When researchers tested menopausal hormone therapy in proper trials, the picture was mixed. A review of more than thirty trials found no overall effect on thinking, although some results varied with the type of treatment and when it was started. Sometimes the answer is impressive. Sometimes it is modest. And sometimes the evidence simply isn’t settled yet.

A more useful question than “Are my hormones causing this?” is “Could hormonal changes be one of the things influencing how my brain and body are responding right now?” That question leaves room for the rest of the system.

Notice whether something shows up at the same point in your cycle, gets worse when you’re stressed or sleeping badly, started during a big hormonal change like after a baby or in perimenopause, or gets in the way of work, relationships or daily life. Those patterns are worth noticing, not because every pattern proves a hormonal cause, but because of something simple. Timing is information!