Why Am I So Tired All the Time? The Most Common Causes We See

Persistent fatigue is one of the most common reasons people seek out functional medicine, and one of the most frustrating, because it's rarely caused by just one thing.

When fatigue becomes the norm rather than the exception, especially fatigue that doesn't improve with sleep, it's usually worth looking at several systems together rather than one lab value in isolation.

The most common contributors we see include:

• Thyroid dysfunction, including cases where labs look borderline normal
• Hormonal imbalances, such as low estrogen, progesterone, or testosterone
• Iron or ferritin levels that are low but not low enough to flag as anemia
• Blood sugar swings that leave energy unstable throughout the day
• Poor sleep quality, even when total sleep time looks adequate
• Chronic stress and a disrupted cortisol pattern
• Nutrient gaps, particularly B12, vitamin D, and magnesium
• Underlying inflammation that hasn't been identified yet

Fatigue that's been dismissed as normal aging, stress, or being busy often has an identifiable, addressable driver once someone actually looks for it. The pattern usually isn't one dramatic lab value, it's several things adding up at once.

If you're tired in a way that rest doesn't fix, that's worth investigating properly, not just pushing through.