Does Eating Carbs Make You Sleepy?

Sleepiness has grown continually more common in the United States, according to the Centers for Disease Control and Prevention. While sufficient nightly sleep is key for daytime energy and alertness, your diet can play a role as well.

Carbohydrates can cause blood sugar, digestive and brain chemistry shifts that induce sleepiness. (Image: cyano66/iStock/GettyImages)

Carbohydrates are your body's main energy source, but they can also work against your wellness and energy levels. If your sleepiness is severe or long-lasting, seek guidance from your doctor.

Blood Sugar Effects

After you eat foods containing carbohydrates, your digestive system breaks down the digestible carbs, which enter your bloodstream. As your blood sugar rises, your pancreas produces insulin, a hormone that allows your cells to absorb the sugar.

In response, your body produces the hormone glucagon, which helps keep your blood sugar and energy levels in check. Simple carbohydrates, such as cane sugar and high-fructose corn syrup, cause your blood sugar to spike up more rapidly than slower-moving complex carbohydrates, prevalent in starchy vegetables and whole grains.

The rapid spike from eating simple carbs, particularly in excess or without other foods, can cause your blood sugar to plummet back down, leading to that groggy crashing feeling. A blood sugar drop of more than 15 percent below fasting level is considered hypoglycemia, or low blood sugar.

Serotonin and Tryptophan

Serotonin and tryptophan may be the reason you feel sleepy after Thanksgiving turkey and mashed potatoes. Carbohydrates allow your brain to produce serotonin, a chemical that allows for calm and pleasant moods, while making tryptophan, the chemical responsible for sleepiness, more available to your brain.

This is one reason carbohydrate-rich meals make you sleepy, says the National Sleep Foundation, and why ideal bedtime snacks contain carbohydrates and protein, a provider of tryptophan.

Drowsiness From Overeating

Overeating is one of the most common causes of eating-induced sleepiness, according to the dietetic department of the Medical University of South Carolina.

After eating, your body routes more blood to your digestive system. Meals excessive in size require even more blood, which causes temporary deprivation of blood and nutrients in your brain and residual grogginess. While these effects are generally mild, you can prevent them by eating smaller, more frequent meals and snacks.

Sleepy When Desired

If you struggle with bedtime wakefulness, Columbia University Health recommends having a small carbohydrate-containing food, such as warm milk. In addition to carbs, milk provides sleep-friendly tryptophan.

If you find yourself sleeping after lunch, your circadian rhythms — your body's natural sleep and alertness clock — may be a bigger culprit than carbs, says the National Sleep Foundation.

If you aren't able to rest at this time, make sure your lunch isn't too large and contains protein, which helps minimize blood sugar decline and sleepiness. Have a leafy salad topped with grilled chicken and whole-grain croutons, for example, instead of a bowl of pasta.

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