Have you ever had a very productive morning and then suddenly crashed in the afternoon? The afternoon blahs struggle is real.

Sleepiness is driven by circadian rhythms and sleep pressure. Circadian rhythms are greatly impacted by our environment, causing us to feel awake and alert during daylight and tired when it’s dark. Our internal alarm clock, if you will.

Those who study such things call the phenomenon that the longer we’re awake, the more our bodies crave sleep, “sleep pressure.”

Sleep pressure is lowest when we first wake in the morning. In the afternoon, circadian rhythms and sleep pressure battle each other, and the result is likely a bout of yawning.

When your body digests lunch, blood sugar rises and prompts insulin production. Sugars and carbs are digested quickly, prompting a brief energy surge before the extra insulin in the bloodstream causes sluggishness.

Experts say you can stave off sleepiness in several ways. Sometimes it starts with breakfast. Donuts and sugary beverages in the morning will cause an insulin dump and a midday crash. Try switching to something like eggs or whole-grain oatmeal. Complex carbs take longer to digest, which results in less of an insulin spike.

Another way to fend off Mr. Sandman is to be active. Take a walk when you feel drowsy. Research has long tied physical activity to improved alertness and concentration.

If all else fails, a power nap might bail you out. But it’s important to keep your snooze to 20 minutes or less to avoid grogginess.

The bottom line is, it’s natural to hit an afternoon slump. Don’t kick yourself for it, and don’t be afraid to experiment with new tactics and activities to keep your energy high.