Why Am I So Tired During My Period? The Link Between Menstrual Changes and Fatigue in Perimenopause

If you've ever curled up on the couch during your period, utterly drained and wondering, "Why does my period make me so tired?", you're not alone. Fatigue during menstruation is incredibly common—but that doesn't mean it's "just part of being a woman." In fact, research shows that period-related tiredness often has very real, treatable causes, ranging from iron loss to hormonal fluctuations.

What Causes Fatigue During Your Period?

Recent studies reveal a strong connection between heavy menstrual bleeding (HMB) and fatigue. When you lose more blood than your body can readily replace, your iron stores become depleted. This isn't just about full-blown anemia—even subclinical iron deficiency can leave you feeling completely drained.¹

The clinical data tell a compelling story:²

• Women experiencing 3+ episodes of heavy bleeding within six months were 62% more likely to feel constantly tired
• They also reported 44% higher rates of feeling "worn out"

This fatigue during your period most often occurs because iron is essential for producing hemoglobin, which carries oxygen to your cells. Without enough iron, your body struggles to deliver oxygen efficiently, leaving you feeling sluggish and weak.³

If you regularly experience heavy bleeding (soaking through a pad or tampon every hour or passing large clots), it's worth discussing iron level testing with your healthcare provider. The good news? Iron deficiency can often be managed through dietary changes, dietary supplements, or medical/surgical treatments.⁴

Nutritional Impact on Fatigue While on Your Period

Heavy periods deplete more than just your iron stores:^5,6

• Zinc and B-vitamin levels often drop with significant blood loss
• These nutrients play crucial roles in energy production 
• Magnesium deficiency, also common in women, can exacerbate fatigue and muscle weakness while on your period

Hormones Contribute to Low Energy Before Your Period

Your reproductive hormones significantly influence your energy levels throughout your menstrual cycle. In the days leading up to menstruation, progesterone levels drop sharply, which can disrupt sleep and leave you feeling groggy.⁷ Simultaneously, estrogen—which helps regulate serotonin, a key player in mood and energy—also decreases. This hormonal double whammy explains why so many women experience low energy before their period starts, often accompanied by mood swings and irritability.⁸

While some women experience mild symptoms, others find this hormonal shift debilitating. Tracking your symptoms can help you and your healthcare provider identify patterns and explore solutions, such as hormonal birth control or lifestyle adjustments.

Inflammation and Sleep Disruptions May Contribute to Extreme Fatigue While on Your Period

Menstruation is fundamentally an inflammatory process. As your uterus sheds its lining, it releases prostaglandins—compounds that trigger contractions (hello, cramps) and can contribute to flu-like fatigue.⁹ This inflammation, combined with period-related discomfort, often leads to poor sleep quality, creating a vicious cycle of exhaustion and extreme fatigue while on your period.¹⁰

In fact, period symptoms can significantly disrupt your sleep:^11,12

• Pain and discomfort lead to 30% more nighttime awakenings
• Hormonal changes reduce REM sleep when you need it most
• Poor sleep worsens pain perception the next day

If you find yourself tossing and turning during your period, prioritizing sleep hygiene can make a big difference. It could help to maintain a consistent bedtime, along with avoiding caffeine in the afternoon, and creating a relaxing pre-sleep routine. Over-the-counter pain relievers, like ibuprofen, may also help reduce inflammation and improve sleep when cramps keep you awake.

What You Can Do About Menstrual Changes and Fatigue in Perimenopause

While some fatigue during your period is normal, extreme exhaustion shouldn't be dismissed. Here's what you can do:^{13,14,15,16,17,18,19}

1. Get proper testing: Consider requesting a ferritin test (which measures iron stores) in addition to standard hemoglobin and hematocrit checks. Optimal ferritin levels for energy are >50 ng/mL
2. Consider strategic supplementation: Iron bisglycinate is gentler on digestion than other forms. Consider taking it with vitamin C for better absorption, and look into magnesium glycinate at night to improve sleep quality
3. Adjust your nutrition: Increase your intake of protein and iron-rich foods (i.e. think green leafy vegetables or red meat) during menstruation, stay hydrated with electrolyte-rich fluids, and limit inflammatory foods that can worsen fatigue
4. Explore hormonal support: Low-dose birth control can help regulate heavy bleeding,
5. Incorporate restorative movement: Gentle yoga can help to reduce inflammation and fatigue, while walking can help to boost circulation without draining your energy

When to Seek Help for Low Energy and Fatigue on Your Period

Consider consulting with your healthcare provider if you experience:

• Fatigue that persists beyond your period
• Needing to change a pad or tampon hourly
• Passing large clots (quarter-sized or bigger)
• Dizziness or shortness of breath with your cycle

Fatigue During Your Period Can Be Manageable

Period fatigue is your body signaling for support, not a sign of weakness. With the right combination of medical insight and self-care, you can transform your cycle from an energy drain to a manageable part of your life. By understanding the science behind menstrual fatigue and implementing research-backed solutions, you can reclaim your vitality throughout your entire cycle. 

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Resources:

1. https://www.ajog.org/article/S0002-9378(23)00024-8/fulltext
2. https://menopause.org/wp-content/uploads/press-release/MENO-D-24-00371.pdf
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC11869313/
4. https://www.fertstert.org/article/S0015-0282(22)00533-7/fulltext
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC11869313/
6. https://pubmed.ncbi.nlm.nih.gov/25627706/
7. https://www.contemporaryobgyn.net/view/heavy-menstrual-bleeding-linked-to-fatigue-in-menopausal-women
8. https://pmc.ncbi.nlm.nih.gov/articles/PMC6500811/
9. https://pubmed.ncbi.nlm.nih.gov/22934724/
10. https://pmc.ncbi.nlm.nih.gov/articles/PMC5406716/
11. https://pubmed.ncbi.nlm.nih.gov/31086516/
12. https://www.contemporaryobgyn.net/view/heavy-menstrual-bleeding-linked-to-fatigue-in-menopausal-women
13. https://pubmed.ncbi.nlm.nih.gov/21496802/
14. https://pmc.ncbi.nlm.nih.gov/articles/PMC11869313/
15. https://www.ajog.org/article/S0002-9378(23)00024-8/fulltext
16. https://pmc.ncbi.nlm.nih.gov/articles/PMC5406716/
17. https://www.fertstert.org/article/S0015-0282(22)00533-7/fulltext
18. https://pubmed.ncbi.nlm.nih.gov/25627706/
19. https://pubmed.ncbi.nlm.nih.gov/22934724/