10. You’ve started a new medication
Fatigue is one of the most common side effects of pharmaceutical medications, with anti-hypertensives, narcotics, anxiolytics and antidepressants being the most common culprits. When you first begin a new medication, give your body some time to adjust. However, if drowsiness persists for several weeks and begins to interfere with your daily life, it’s time to see a doctor.