Perimenopausal Fatigue and Slowing Down: Why Your Energy, Brainpower, and Performance Might Be Shifting

You’ve always been the type to go full speed. Whether it’s early morning workouts, high-pressure projects, or balancing home life like a pro—fatigue was never your thing. But lately, you're dragging. Your brain feels foggy, your workouts seem harder, and you're wondering if you’re just burning out or if something deeper is going on.

If this sounds familiar, you’re not imagining it. Perimenopausal fatigue and slowing down are very real, very common, and very frustrating. The good news is that there are reasons—and solutions.

Perimenopause is the hormonal transition phase before menopause, often beginning in your 40s, though it can start earlier. It can last anywhere from 4 to 10 years. During this time, estrogen and progesterone levels fluctuate unpredictably, affecting everything from your mood to your metabolism.

Fatigue during this stage is often caused by a combination of hormonal chaos, poor sleep, and brain fog. Estrogen plays a role in regulating energy and mood, and when its levels fluctuate, your energy can drop. Many women also report night sweats, insomnia, or disrupted REM sleep that leave them feeling unrested. Brain fog, characterized by difficulty concentrating, memory lapses, and a sense of mental “slowness,” is also extremely common. A 2021 study in the journal Menopause found that nearly 85% of perimenopausal women reported some degree of fatigue, often tied to sleep issues and mood instability.

Cognitive symptoms like brain fog are not just in your head. Declining estrogen affects neurotransmitters like serotonin and dopamine, which are essential for cognitive function and focus. Many women notice that they forget names or words, struggle to stay organized, or feel less sharp at work. Research from Harvard Medical School has shown that working memory and attention can dip during the perimenopausal years but often stabilize after menopause.

Physically, you might notice that you’re slowing down. You may have less stamina, need more effort for the same results, or find that muscle recovery takes longer. Estrogen plays a role in muscle mass, circulation, and thermoregulation. As estrogen declines, your aerobic capacity may decrease, and your ability to recover may diminish—even if your training hasn’t changed. A 2023 meta-analysis published in Sports Medicine found that perimenopausal athletes often experience declines in performance, not because they are doing anything wrong, but due to natural hormonal shifts.

Fortunately, there are steps you can take to support your body during this transition.

First, prioritize sleep. This means creating a consistent bedtime routine, avoiding screens before bed, and possibly considering supplements like magnesium glycinate or melatonin, after consulting your healthcare provider. Second, balance your blood sugar by eating high-protein, low-sugar meals, cutting back on processed carbs and alcohol, and staying well hydrated. Even mild dehydration can worsen fatigue.

When it comes to exercise, try to move smarter, not harder. Strength training can help preserve muscle mass and bone health. Using tools like heart rate variability to guide workout intensity can be helpful. Don’t hesitate to take rest days; they are not a sign of weakness, but a vital part of performance and recovery.

Finally, talk to your healthcare provider about hormonal support. Hormone replacement therapy (HRT) can be life-changing for some women. Others may benefit from non-hormonal treatments such as SSRIs or adaptogens. It’s also important to rule out other medical issues like thyroid dysfunction, anemia, or vitamin B12 deficiency with appropriate lab testing.

Slowing down in perimenopause is not a personal failure—it’s your body sending you important messages. The fatigue and brain fog are not signs of weakness, but part of a biological transition that millions of women go through every year. With the right support and a shift in how you approach energy, performance, and recovery, you can continue to thrive—mentally, physically, and emotionally.

References

1. Freeman EW et al. “Symptoms associated with menopausal transition.” Menopause. 2021.

2. Brinton RD. “Estrogen regulation of glucose metabolism and mitochondrial function: therapeutic implications for prevention of Alzheimer’s disease.” Adv Drug Deliv Rev. 2008.

3. Harvard Health Publishing. “Menopause and your memory.” Harvard Medical School.

4. Elliott-Sale KJ et al. “Hormone fluctuations and athletic performance in female athletes.” Sports Medicine. 2023.

5. North American Menopause Society (NAMS). https://www.menopause.org