Why Do I Have So Much Fatigue After 40?

A tired woman in an apron stands in a doorway with her eyes closed, looking exhausted.

Fatigue is one of the most common complaints I hear from women over 40. You wake up tired, push through the day with coffee or sheer willpower, and by evening, you’re running on empty, again. For many women, this feels like an unavoidable part of aging. But here’s the truth: persistent fatigue after 40 is common, but it’s not inevitable.

If you’ve been wondering why your energy seems to have disappeared overnight, you’re not alone. Let’s dive into the most common reasons women over 40 feel so tired, the red flags you shouldn’t ignore, and holistic strategies to help you reclaim your energy and vitality.

Common Causes of Fatigue After 40

Fatigue is rarely caused by one single factor. Instead, it’s often the result of several overlapping changes in hormones, lifestyle, nutrition, and even stress levels.

1. Hormonal Shifts

During perimenopause and menopause, your levels of estrogen and progesterone naturally decline. These hormones influence everything from mood to sleep quality, and when they shift, energy often dips. Thyroid function can also fluctuate during this stage of life, further contributing to fatigue.

  • Estrogen: Low levels can affect sleep and mood.
  • Progesterone: Decline can lead to anxiety and restlessness at night.
  • Thyroid: Hypothyroidism (underactive thyroid) is more common in midlife and can cause fatigue, brain fog, and weight gain.

2. Poor Sleep Quality

Even if you spend eight hours in bed, you may not be getting restorative sleep. Women over 40 are more likely to experience:

  • Hot flashes or night sweats disrupting sleep cycles
  • Sleep apnea, which prevents deep rest
  • Insomnia due to stress or hormone changes

Studies show that disrupted sleep patterns in midlife women are strongly linked to daytime fatigue, mood swings, and reduced quality of life (Li & Zhang, 2019).

3. Nutrient Deficiencies

Low energy can sometimes be traced back to missing nutrients. Common culprits include:

  • Iron – essential for carrying oxygen through the blood; low iron often causes fatigue
  • Vitamin B12 – supports red blood cell production and brain health
  • Vitamin D – deficiency can cause tiredness, low mood, and muscle weakness
  • Magnesium – helps regulate sleep, muscle function, and energy production

Because absorption can decrease with age, women over 40 may need to pay closer attention to these nutrients through diet or supplementation.

4. Stress & Cortisol Imbalance

Chronic stress doesn’t just affect your mood; it wears your body down physically. Prolonged stress can dysregulate the HPA axis (the system that controls cortisol production), leading to burnout, weight gain, and constant fatigue. When cortisol is out of balance, you may feel:

  • Wired but tired at night
  • Sluggish in the morning
  • Dependent on caffeine to “get going”

This pattern isn’t just exhaustion …it’s your body’s stress response stuck on repeat.

5. Medications & Medical Conditions

Some medications commonly prescribed after 40 may cause fatigue as a side effect. These include antidepressants, antihistamines, blood pressure medications, and even GLP-1 weight loss medications. While GLP-1s are powerful tools for weight loss, they can sometimes lead to fatigue if nutrition and hydration aren’t optimized. Other medical conditions linked to midlife fatigue include:

  • Diabetes or insulin resistance
  • Anemia
  • Heart disease
  • Autoimmune conditions
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When Fatigue After 40 Is a Red Flag

It’s normal to have the occasional tired day. But persistent fatigue that doesn’t improve with rest may indicate something deeper. Call your provider if:

  • You’ve been fatigued for more than a few weeks without improvement
  • You also have unexplained weight changes, hair loss, or brain fog
  • You experience shortness of breath, chest pain, or dizziness
  • You struggle with insomnia most nights
  • You’re constantly relying on caffeine just to function

These could point to underlying health conditions like thyroid disorders, anemia, or sleep apnea …all of which are treatable with the right care.

Holistic Ways to Reclaim Energy After 40

At Ample Health & Wellness, I encourage women to look at fatigue from a whole-body perspective. That’s where my FRESH Framework comes in because energy is about much more than a quick fix.

F – Food Freedom

Nutrition is foundational for energy. Instead of skipping meals or surviving on coffee, focus on balanced, anti-inflammatory meals.

  • Include lean protein at each meal to stabilize blood sugar.
  • Add high-fiber carbs (like oats, quinoa, or sweet potatoes) for steady energy.
  • Incorporate omega-3s from salmon, walnuts, or chia seeds to reduce inflammation.

R – Rewire the Mindset

Mindset and stress management are crucial for fighting fatigue.

  • Practice mindfulness or journaling to reduce stress.
  • Use breathwork or meditation to reset cortisol rhythms.
  • Challenge the belief that exhaustion is “just aging.”

E – Elevate with Habits

Movement creates energy. It may feel counterintuitive when you’re tired, but regular activity helps reduce fatigue over time.

  • Start with walking or gentle yoga.
  • Add strength training twice a week to support metabolism.
  • Take movement breaks during the workday to avoid stiffness and sluggishness.

S – Simplify Your Environment

Your environment can either drain or energize you.

  • Prioritize sleep hygiene: dark, cool bedroom, consistent bedtime, and limited screen use before bed.
  • Reduce clutter in your home or workspace to lower stress.
  • Build routines that simplify your daily choices, like meal prep or scheduled movement.

H – Honor Whole Health

True energy comes from caring for your whole self.

  • Stay hydrated throughout the day.
  • Schedule regular checkups to monitor thyroid, blood sugar, and nutrient levels.
  • Lean into supportive relationships and community.
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The Bigger Picture

Fatigue after 40 isn’t just about aging. It’s your body’s way of signaling that it needs more care, balance, and nourishment. By addressing the root causes (hormones, sleep, nutrition, stress, and lifestyle) you can regain energy and resilience. You deserve to feel vibrant, not drained. With the right holistic strategies, it’s possible to wake up energized, stay focused throughout the day, and enjoy life after 40 with more vitality than ever.


At Ample Health & Wellness, I help women over 40 rebuild their energy, balance hormones, and create sustainable routines that fight fatigue while supporting weight loss. Learn more inside my FRESH Start Holistic Weight Loss Program and grab a copy of my book The Weight Is Over at amplehealthandwellness.com.

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