First Signs of Perimenopause You Shouldn’t Ignore
Dec 15, 2025
Most women hear about menopause as the moment when periods stop. Far fewer learn about perimenopause, the long transition that comes before it. What often surprises people is that the first signs of perimenopause can begin in the late thirties or early forties. Many notice changes long before they expect any major hormonal shifts.
The most famous signs of perimenopause are menstrual cycle irregularity and the onset of vasomotor symptoms, particularly hot flashes and night sweats. These changes typically begin in the mid-to-late 40s, with the median age at perimenopause being around 47.5 years [1]. Menstrual cycles may become shorter, longer, or more variable, and flow may change in volume or duration [2]. Vasomotor symptoms, hot flashes, and night sweats are the most specific and reliable indicators of the transition, especially when they become moderately to severely bothersome [3]. And though there’s so much more to know about the symptoms of perimenopause, especially the earliest signs, I’ll leave those details for another post and focus more on what’s actually happening in the body to cause this chaos.
The Quiet Shift Behind Everything
Perimenopause begins with changes in your hormones. Oestrogen and progesterone start to move in unpredictable ways. Your ovaries make less of these hormones over time. This is why your cycle may feel irregular.
These hormonal changes lead to a cascade of effects:
- First, Progesterone levels begin to drop, which means less of its calming influence on GABA (the brain’s “relaxation” neurotransmitter).
- Then, estrogen levels begin to dip, or even rise erratically, which affects mood-regulating brain chemicals like serotonin and norepinephrine.
- The hypothalamus (the brain centre for temperature regulation, sleep, and hormone feedback) becomes more sensitive to even tiny fluctuations and your body starts to feel out of whack.
In real life, this might look like stronger emotional reactions. You might notice mood swings. Your sleep might change. Your energy might be up one day and down the next. Many women notice anxiety or irritability even before hot flashes start.
Irregular Periods: The Most Recognized Early Signal
When you look at studies and medical research, changes in your menstrual cycle are the first sign that perimenopause has begun. Your periods may come sooner or later than usual. They may become heavier or lighter. You might skip a period with no clear reason. PMS may feel different too.
Common changes include:
- Cycles are getting shorter or longer.
- Heavier or lighter bleeding.
- Changes in PMS pattern.
- Periods are skipped without explanation.
Your periods may arrive closer together or further apart, or be longer or shorter than usual … and all of this is due to fluctuations in the amount of oestrogen and progesterone in your body.
A New Chapter of Symptoms
When you delve deeper into the research on women’s health and go beyond the conventional medicine’s school of thought, a much better understanding of perimenopause emerges. The real early symptoms can include mood changes (such as increased anxiety, irritability, or depressive symptoms), sleep disturbances, and cognitive complaints like poor memory or "brain fog" [4]. Genitourinary symptoms (vaginal dryness, dyspareunia, urinary urgency) may also begin but are less specific to the early transition and tend to happen in post-menopause. While many symptoms (fatigue, headache, anxiety) are prevalent across all reproductive stages, the combination of cycle irregularity and vasomotor symptoms is most indicative of perimenopause onset [3].
What matters most is the overall pattern your body is showing you. If you are seeing irregular cycles along with hot flashes or night sweats, then you’re in perimenopause. But if you’re getting those other subtle symptoms where you’re just not feeling like your usual self, something is off in your mid-40’s and you’re wondering if hormones has something to do with it, then it’s worth investigating it. You are not imagining it and you should not gaslight yourself. Speak up. You are not alone in it. And your body is simply asking you to pay closer attention, and you should.
Understanding Early Signs Helps You Take Back Control
Recognizing the first signs of perimenopause is not about expecting the worst. It is about understanding your body so you can feel steadier and more prepared. When you know what is happening, you can move through this stage with confidence instead of confusion.
At The Perimenopause Lab, my mission is simple. I want women to feel seen and supported. I help health-conscious women move from hormonal chaos to clarity. I do this with data-driven and holistic strategies that are practical and easy to understand.
You deserve to feel informed. You deserve to feel in control. The early signs of perimenopause do not have to feel frightening. They can simply be the start of a better understanding of your body. And because I know that all these symptoms can get confusing, I’m working on a symptom decoder for you. As soon as a beta version is ready, I’ll post about it!
Let’s Stay Connected
If this blog resonates with you, share it with a friend who might be going through the same changes. Sometimes a simple conversation can remind someone that she’s not alone.
You can also connect with me and join our growing community. Together, we’ll keep learning, sharing, and supporting each other through every stage of this transition.
Every follow, share, and message helps another woman feel seen, supported, and understood. Thank you for being part of this community.
Questions that have come up this week:
1. How do you know perimenopause is starting?
Officially, perimenopause begins when your cycle becomes more unpredictable (+/- 7 days in length, is the specific number from the Menopause Society). Later in the transition, you may go sixty days or longer without a period, until menopause (defined as 12 months without a period). But the research is growing, and so is the definition of what women go through. Perimenopause is starting to include the late reproductive stages when symptoms of hormone irregularities related to ovarian aging start to appear. The signs and symptoms vary greatly, as does the age of onset. So open-minded practitioners who are dedicated to supporting women fully and holistically will rely on good listening skills to understand the symptoms described and match those to hormonal patterns that may indicate a perimenopause transition.
2. What does perimenopause fatigue feel like?
Perimenopause fatigue often feels deeper than regular tiredness. Many women describe it as a steady, low energy that does not fully improve with rest. You don’t wake up refreshed, you have an afternoon crash, and you’re just running at 40% battery. It can affect your ability to focus or cope with daily stress. You may feel unlike yourself or notice brain fog or slower thinking. It is important to rule out or distinguish this fatigue from other conditions like anemia, hypothyroidism, or burnout, so some investigations would be necessary before any practitioner could definitively point to perimenopause. Nonetheless, those symptoms are real and worth talking about, so you can find a resolution that works for you.
3. What not to do during perimenopause?
Don’t be too hard on yourself or undermine what you’re feeling. As more women speak up, recognition is increasing, and with it, the research and support are growing too. Don’t bear it in silence, or feel afraid to talk about it. This is a natural transition, and being vocal about it allows the support and solutions to emerge.
Sources:
- Bastian, Lori A., Crystal M. Smith, and Kavita Nanda. "Is this woman perimenopausal?." Jama 289, no. 7 (2003): 895-902. doi:10.1001/jama.289.7.895
- Crandall, Carolyn J., Jaya M. Mehta, and JoAnn E. Manson. "Management of menopausal symptoms: a review." Jama 329, no. 5 (2023): 405-420. doi:10.1001/jama.2022.24140
- Islam, Rakibul M., Molly Bond, Aida Ghalebeigi, Yuanyuan Wang, Karen Walker-Bone, and Susan R. Davis. "Prevalence and severity of symptoms across the menopause transition: cross-sectional findings from the Australian Women's Midlife Years (AMY) Study." The Lancet Diabetes & Endocrinology 13, no. 9 (2025): 765-776. doi: 10.1016/S2213-8587(25)00247-5. PMID: 40720963.
- Verrilli, Lauren, and Sarah L. Berga. "What every gynecologist should know about perimenopause." Clinical Obstetrics and Gynecology 63, no. 4 (2020): 720-734. doi: 10.1097/GRF.0000000000000578. PMID: 33044248.
