What causes energy crashes in the middle of the day?

Midday energy crashes are primarily caused by a combination of your circadian rhythm and blood sugar fluctuations. Around early afternoon, your body experiences a natural dip in alertness driven by your internal clock, which is separate from whether you ate lunch or not. This dip typically occurs between 1 and 3 PM. Meals amplify this effect significantly. High-carbohydrate or sugary foods cause a rapid spike in blood sugar followed by a sharp drop, triggering fatigue and brain fog. Insulin released after eating also promotes tryptophan uptake in the brain, increasing serotonin and melatonin production, which induces drowsiness. Dehydration, poor sleep the night before, and sedentary behavior all make the crash worse.