What causes afternoon fatigue and how do you fix it?

Afternoon fatigue is primarily caused by your circadian rhythm, which naturally dips in alertness between 1-3pm regardless of how much sleep you got. It's compounded by large lunches that spike blood sugar followed by a crash, dehydration, and accumulated sleep debt from the night before. To fix it, eat a lighter lunch with protein and healthy fats instead of heavy carbs, drink water consistently throughout the day, and get 10-20 minutes of sunlight or physical movement around midday. A short 10-20 minute nap can restore alertness without causing grogginess. Long-term, prioritizing 7-9 hours of sleep at night is the most effective solution since the afternoon dip becomes far more pronounced when you're already sleep-deprived.