What Are the Early Signs of Perimenopause?
A Clear, Science‑Backed Guide for Women Who Feel “Not Quite Themselves”
Perimenopause is the hormonal transition leading up to menopause and for many women, it’s the stage where symptoms begin long before periods stop. Yet most women aren’t told what early perimenopause actually looks like. Instead, they’re told they’re “too young,” “just stressed,” or “probably fine.”
But research shows that early symptoms can begin in the mid‑40s and for some women, even in their mid‑30s. Understanding these early signs can help you make sense of changes in your mood, energy, sleep and cycle and stop second‑guessing yourself.
Below is a clear, evidence‑based breakdown of what the early phase really looks like.
1. Irregular or Changing Menstrual Cycles
The most reliable early sign of perimenopause is a shift in your cycle pattern.
Common changes include:
Shorter cycles (e.g., 21–24 days instead of 28)
Heavier or lighter bleeding
Mid‑cycle spotting
Periods that arrive early one month and late the next
These changes reflect the first stage of the menopausal transition as defined by the STRAW+10 criteria, the international gold standard for staging reproductive aging.
Key research:
The STRAW+10 framework identifies cycle variability as the earliest measurable marker of perimenopause (PMID: 22343510).
2. Hot Flushes and Night Sweats; Yes, They Can Start Early
Many women assume hot flashes only happen “right before menopause,” but studies show they can begin years earlier.
A major cross‑sectional study found that moderate‑to‑severe vasomotor symptoms (VMS) were five times more common in perimenopausal women than in premenopausal women (PMID: 34033602).
Early VMS often look like:
Sudden warmth in the chest, neck, or face
Night sweats that disrupt sleep
Feeling flushed without sweating
These symptoms are strongly linked to fluctuating oestrogen levels not low levels, but instability.
3. Sleep Disturbances and Early‑Morning Waking
Sleep changes are one of the most common early complaints.
Women often report:
Waking at 3–4am for no reason
Difficulty falling back asleep
Feeling unrefreshed despite “sleeping enough”
Research shows that hormonal variability affects the brain’s temperature regulation and sleep‑wake cycles, contributing to disrupted sleep (PMID: 40750881).
4. Anxiety, Mood Swings and Feeling “Emotionally Volatile”
Perimenopause is not a mental health disorder but hormonal fluctuations can affect neurotransmitters such as serotonin and GABA.
Common early emotional symptoms:
Sudden anxiety
Irritability or “short fuse”
Feeling overwhelmed by things that never used to bother you
Mood dips around ovulation or before your period
Longitudinal studies show increased vulnerability to mood symptoms during the menopausal transition, especially in women sensitive to hormonal change (PMID: 20530009).
5. Brain Fog and Concentration Problems
Many women describe:
Losing words
Forgetting what they walked into a room for
Difficulty focusing
Feeling mentally “slower”
This is linked to fluctuating oestrogen’s impact on the prefrontal cortex and hippocampus areas involved in memory and executive function.
A review in The Journal of Clinical Endocrinology & Metabolism highlights cognitive changes as a recognised feature of the transition (PMID: 27793768).
6. Fatigue That Doesn’t Improve With Rest
This is one of the most common early symptoms and one of the most dismissed.
Fatigue in early perimenopause is often:
Sudden
Persistent
Out of proportion to daily demands
Worse around cycle changes
Hormonal variability affects sleep, stress response and metabolic regulation, a triple hit that can leave women feeling depleted.
7. New or Worsening PMS
If your PMS suddenly intensifies in your 40s, it may be an early sign of perimenopause.
This includes:
Stronger mood swings
Breast tenderness
Cramping
Irritability
Low mood
This pattern is linked to declining progesterone and fluctuating oestrogen.
8. Reduced Stress Tolerance
Women often say:
“I can’t cope the way I used to.”
“Small things feel huge.”
“My resilience has dropped.”
This is not a personality change, it’s physiology. Hormonal instability affects the HPA axis (the stress‑response system), making stress feel more intense.
So… Is What You’re Feeling Normal?
If you’re in your late 30s, 40s or early 50s and experiencing a mix of these symptoms, yes, this pattern is consistent with early perimenopause.
Blood tests often appear “normal” in this stage because the defining feature is fluctuation, not deficiency.
International menopause societies, including the British Menopause Society, emphasise that diagnosis should be based on age, cycle changes and symptoms, not lab results.
Why Early Recognition Matters
Understanding early perimenopause helps you:
Stop blaming yourself
Stop assuming it’s “just stress”
Seek appropriate support
Adjust routines to match your physiology
Protect long‑term health (bone, heart, metabolic)
Most importantly, it gives you back a sense of control.
If you’d like more clarity about what’s happening in your body and a practical way to track the changes you’re noticing you can download my free Perimenopause Blueprint. I also have a free Perimenopause Symptom Tracker, contact me to send it over! Together, they help you recognise patterns, understand the science behind your symptoms and have clearer conversations with your doctor. You’ll also receive my monthly newsletter, where I share steady, evidence‑based guidance to support you through midlife.
References
STRAW+10 criteria for staging reproductive aging — PMID: 22343510
Vasomotor symptoms as early markers of perimenopause — PMID: 40720964
Mood vulnerability during the menopausal transition — PMID: 39111089
Cognitive changes in perimenopause — PMID: 37755656
Hormonal mechanisms of perimenopause — PMID: 26653408
