Feeling sleepy after eating a sugary snack such as chocolate is normal. Large quantities of chocolate can lead to a rapid rise in blood sugar and a consequent drop below normal levels. The result is fatigue. While this is usually not a cause for concern, it can occasionally point to something serious, such as diabetes. If you experience blurred vision, extreme fatigue and increased thirst, consult a doctor to determine the cause.
Why You Feel Tired
When you eat chocolate, which is high in carbohydrates and sugar, your pancreas responds by producing high amounts of insulin and other hormones to regulate your blood-sugar levels. The insulin reduces sugar and amino acids in the blood, except for tryptophan, an amino acid. This process allows the brain to absorb more tryptophan, which converts to serotonin, a brain chemical that makes you feel tired, according to Columbia Health. This can occur in healthy people as well as those with problems such as diabetes.
Possibility of Diabetes
If your doctor suspects your post-meal fatigue is caused by diabetes, he will order a blood test. There are two main form of diabetes -- type-1 and type-2. Either can cause fatigue after a carbohydrate-rich snack such as chocolate, but type-2 diabetes is much more common. Even if you don't experience symptoms other than fatigue -- such as blurred vision, slowed wound healing and frequent urination -- you may have prediabetes, which has few or no symptoms.
Dark Chocolate Beats Fatigue
Dark chocolate is richer in cocoa and contains less sugar than milk chocolate. Therefore, it is less likely to cause an insulin spike and induce fatigue. Dark chocolate contains caffeine, and it might help alleviate symptoms of chronic fatigue syndrome. The higher the percentage of the dark chocolate cacao, the less sugar and milk it contains. If you are sensitive to caffeine's effects, eat dark chocolate only in small amounts.
You can avoid feelings of fatigue by cutting back on milk chocolate. Other sugary foods and high-carb meals, such as baked goods and pasta, can also produce the same effects. This is especially important if you have diabetes because blood-sugar spikes can have life-threatening consequences. Foods rich in fiber are less likely to cause blood-sugar spikes because they don't require insulin for digestion. Enrich your diet with fibrous foods such as green salads, oats, whole-grain bread, nuts and beans.