That overwhelming drowsiness during your early afternoon meeting may not simply be due to fatigue or lack of sleep—it could be caused by a blood sugar spike.
A blood sugar spike refers to a rapid rise in blood glucose levels after eating, followed by a sharp drop. These sudden fluctuations can lead to sleepiness and fatigue, ultimately reducing work performance.
Benedict, C., et al. “Postprandial glycemic control and cognitive function.” Am J Clin Nutr. 2012;95(1):80–86.
Consuming highly refined carbohydrates—such as white rice, bread, or noodles—on their own can trigger a rapid increase in blood sugar. Think of it as a “runaway car”: glucose levels accelerate uncontrollably, then crash, leaving you feeling drowsy.
On the other hand, starting your meal with vegetables, protein, and healthy fats slows down digestion and absorption, helping to prevent sharp spikes in blood sugar.
One study reports that individuals with greater post-meal blood sugar fluctuations tend to experience declines in attention and memory. This is rooted in physiological mechanisms.
Smith, M. A., et al. “Glycemic variability and cognitive performance.” Diabetes Care. 2017;40(4):554–561.
Eat in this order: vegetables → protein → carbohydrates. A traditional set meal style (like a Japanese teishoku) is ideal.
If you’re having a convenience store lunch, simply add a salad or soup. This alone can help moderate blood sugar spikes.
Light physical activity helps stabilize blood sugar and prevent drowsiness.
Colberg, S. R., et al. “Exercise and glycemic control after meals in type 2 diabetes.” Diabetes Care. 2009;32(11):2109–2111.
Managing blood sugar spikes is not only important for preventing diabetes—it directly improves your afternoon productivity.
“It’s not your fault you feel sleepy in the afternoon.”
“But you can change your performance by changing how you eat.”Blood sugar management is a form of self-investment for modern professionals.
