When It’s Not Just Perimenopause: Understanding Midlife Symptom Overlap

As a nurse practitioner working in women’s health and longevity, I see this pattern too often:

A woman in her mid 40s or early 50s comes in exhausted, foggy, anxious, not sleeping, gaining weight despite doing “all the right things,” and feeling unlike herself. Somewhere along the way, she’s been told “It’s probably perimenopause.”

Sometimes, that’s absolutely true.

But just as often, perimenopause is only part of the picture — or not the explanation at all.

Perimenopause shares symptoms with many health conditions. Knowing the difference matters – not just for symptom relief, but for long-term health.  

Why “It’s Just Perimenopause” Is So Common

Perimenopause is the hormonal transition leading up to menopause and can begin as early as 8–10 years before the final menstrual period. Estrogen and progesterone fluctuate unpredictably during perimenopause, which explains why symptoms can feel chaotic and do not always match with the lab results, which may be “normal”. Because of the fluctuations in hormones during perimenopause, diagnosis and management depends largely on symptoms rather than labs.

Common perimenopause symptoms include:

• Fatigue
• Brain fog, difficulty concentrating
• Hot flashes or temperature dysregulation
• Sleep disruption
• Irregular menstrual cycles
• Anxiety or mood changes
• Reduced stress tolerance
• Weight gain
• Palpitations
• Decreased libido
• Vaginal dryness or discomfort

Here’s the challenge: none of these symptoms are specific to perimenopause alone.

In clinical practice, I often see women whose symptoms were attributed to hormones for years, only to discover an underlying, treatable condition.

Common Treatable Conditions that Mimic Perimenopause 

1. Thyroid Disorders

Thyroid conditions affect many of the same systems as perimenopause, including energy, mood, sleep, and temperature regulation. An underactive thyroid may cause fatigue, weight gain, irregular periods, hair thinning, and low energy, while an overactive thyroid can trigger anxiety, palpitations, weight loss, and heat intolerance. Even mild thyroid dysfunction can produce symptoms.

Overlap with perimenopause:

• Fatigue and low energy
• Weight changes
• Anxiety or low mood
• Hair thinning
• Palpitations
• Heat or cold intolerance
• Menstrual changes

How it is tested:

The main test is TSH (Thyroid Stimulating Hormone). Additional supporting tests such as T4, T3 and TPO antibodies may be helpful in further determining if a thyroid disorder is present. 

2. Iron Deficiency

Iron is critical for energy, brain function, and oxygen delivery. Low iron can cause fatigue, brain fog, dizziness, palpitations, poor sleep, hair thinning, and reduced exercise tolerance—often mistaken for hormonal changes. Because iron deficiency can occur even when hemoglobin is normal, it is frequently missed. Iron deficiency can occur even when hemoglobin levels are normal, so it may be missed unless ferritin and iron studies are also checked. Iron deficiency is extremely common in women, particularly those experiencing heavier or more frequent bleeding during perimenopause.

Overlap with perimenopause:

• Persistent fatigue
• Brain fog and poor concentration
• Palpitations
• Hair shedding
• Increased anxiety

How it is tested:

• CBC (Complete Blood Count)
• Ferritin
• Iron Panel

3. Micronutrient Deficiencies

Deficiencies in B vitamins, vitamin D, or magnesium can produce fatigue, mood swings, poor sleep, brain fog, and muscle aches—symptoms commonly attributed to perimenopause.

Overlap with perimenopause:

• Vitamin B12: fatigue, brain fog, mood changes
• Vitamin D: muscle pain, and possibly fatigue and low mood (that is a whole other blog post!)
• Magnesium: poor sleep, headaches

Women with digestive disorders, restrictive diets, or chronic stress are particularly vulnerable. Correcting deficiencies can lead to noticeable improvement.

How it is tested:

• Vitamin B12
• Vitamin D
• Magnesium

4. Alcohol Use

Even moderate alcohol intake can worsen or mimic perimenopause symptoms, including hot flashes, night sweats, palpitations, sleep disruption, brain fog, and mood changes. Alcohol sensitivity often increases in midlife, meaning previously tolerated amounts may now trigger symptoms more easily. Reducing intake can improve sleep, hormonal balance, immune function, and overall long-term health and longevity.

Overlap with perimenopause:

• Sleep disturbances
• Hot flashes, night sweats
• Fatigue
• Brain fog
• Anxiety, low mood
• Weight changes

How it is tested:

• Experiment with reducing/eliminating alcohol and tracking your symptoms. Then reintroduce it and track again. 

5. Sleep Disorders

Sleep issues—including insomnia, sleep apnea, restless legs, circadian disruptions—can mimic perimenopause because poor sleep affects energy, mood, cognition, and overall wellbeing. Nighttime awakenings may even produce hot-flash–like sensations or palpitations. Identifying and treating sleep disorders is critical, as hormone therapy alone cannot fully address these symptoms.

Symptoms that overlap with perimenopause include:

• Insomnia
• Fatigue
• Anxiety, low mood
• Brain fog, difficulty concentrating
• Hot flashes

How it is tested:

• Self-report questionnaires (eg. Insomnia Severity Index, Menopause Symptom Questionnaire, Stop-Bang)
• Sleep Study

6. Anxiety and Mood Disorders

Anxiety and mood disorders share many symptoms with perimenopause: irritability, mood swings, low energy, sleep disruption, palpitations, and hot-flash–like sensations. Hormonal fluctuations can exacerbate these conditions, even in women with no prior history. Proper evaluation and treatment—through therapy, lifestyle changes, or medication—can improve quality of life, independent of hormones.

Symptoms that overlap with perimenopause include:

• Fatigue
• Sleep disturbances
• Mood changes
• Irritability
• Palpitations

How it is tested:

• Self-report questionnaires (eg. GAD-7, PHQ-9)
• Psychological assessment

7. Insulin Resistance and Metabolic Changes

Weight gain in midlife is often blamed solely on declining estrogen, but insulin resistance is a frequent contributor. It can cause fatigue, brain fog, difficulty losing weight, abdominal fat accumulation, sugar cravings, and mood fluctuations. These metabolic changes may also disrupt sleep and mimic hot flashes. Early identification and lifestyle interventions can significantly improve these symptoms.

Symptoms that overlap with perimenopause include:

• Fatigue
• Brain fog
• Difficulty losing weight
• Irritability
• Hot flashes

How it is tested:

• Fasting insulin
• Fasting glucose
• A1C

The Takeaway

Perimenopause is a natural transition, but its symptoms—fatigue, mood changes, brain fog, sleep disruption, and more—can overlap with a range of other conditions, from thyroid or iron deficiencies to sleep disorders, metabolic changes, and lifestyle factors like alcohol use. Understanding these “perimenopause mimics” is key to addressing the root cause of your symptoms rather than just managing them. 

At NiaHealth, we focus on a holistic approach to midlife wellness, combining evidence-based testing, lifestyle strategies, and targeted interventions to support hormonal health, metabolic health, and overall longevity. By identifying the true drivers behind your symptoms, you can reclaim energy, clarity, and vitality, ensuring that midlife is not just a transition, but a thriving chapter of life.