How are CYP1A2 and fatigue related?

CYP1A2 is a liver enzyme responsible for metabolizing caffeine. Genetic variants (e.g., rs762551) determine whether a person is a fast or slow caffeine metabolizer. Slow metabolizers experience prolonged caffeine elevation, which can disrupt sleep and contribute to daytime fatigue, especially with high caffeine intake. Fast metabolizers clear caffeine quickly but may still feel fatigued if they consume excessive caffeine or have other lifestyle factors. The evidence linking CYP1A2 directly to fatigue is moderate: well-established via caffeine metabolism, but fatigue is multifactorial (sleep, stress, nutrition, exercise). A DNA test can offer insights but should not replace a comprehensive health assessment. Safety note: persistent fatigue warrants checking for other causes like anemia or thyroid disorders.