warum bin ich so müde test — what are common causes?

Fatigue is multifactorial. Common causes include insufficient sleep, chronic stress, poor diet, dehydration, and lack of exercise. Medical conditions like iron-deficiency anemia, hypothyroidism, vitamin D deficiency, or sleep apnea are also frequent. DNA tests (e.g., MyBody-X) may report variants in circadian genes like PER1, but effect sizes are tiny and not clinically actionable. Evidence for genetic testing explaining fatigue is weak (mechanistic/unclear). A thorough medical workup (blood count, thyroid panel, ferritin) is far more informative. Consumer genetic tests are informational, not diagnostic. Caveat: Do not change medications or supplements based solely on such results.