This article explains some theories about why you may feel sleepy after meals and offers some ideas for staying alert after eating.
Elements in Food
There are certain elements within food that can cause sleepiness. However, usually the amounts are small and have little effect on a person’s ability to stay alert. Some things in food that are known sleep inducers include:
Melatonin: There are minuscule levels of the hormone called melatonin in some foods. Although melatonin has an essential role in the timing of sleep, the low levels within food are unlikely to affect sleepiness significantly. Tryptophan: Some other foods might make you feel a little sleepy, most notably turkey and foods that contain an amino acid called tryptophan. The body converts tryptophan to serotonin and then to melatonin. As noted above, this can enhance sleepiness. However, the effects are likely modest. Alcohol: In addition, drinking alcohol may cause drowsiness. It does this because it enhances the effects of adenosine. However, in most cases, this is not what contributes to feeling sleepy after lunch. Carbohydrates: Meals heavy in carbohydrates—which your body converts to sugar—can cause your blood sugar to rise and then crash. This drop in sugar levels can also make you sleepy after eating.
Sleep Drive and Circadian Rhythm
Post-lunch sleepiness often has more to do with the natural timing of an increased tendency towards sleep than the food you consume. Two phenomena contribute to this. They include:
Sleep drive: The sleep drive is due to the gradual build-up of a chemical within the brain called adenosine. This chemical reaches its peak right before bedtime, but it is also higher in the afternoon compared to the morning. Thus, the longer a person stays awake, the more adenosine accumulates, increasing the desire for sleep. Circadian rhythm: The second process that contributes indirectly to sleepiness is the circadian rhythm. The circadian rhythm functions like a clock that controls periods of wakefulness and sleep. It increases throughout the day to keep you awake and counteract the increasing levels of adenosine.
There is a dip in this pattern in the early afternoon. This lull typically occurs seven to nine hours after waking up. When the alerting signal dips, the underlying sleepiness shows itself, and you feel sleepy.
Interestingly, night owls (who may naturally fall asleep and wake later) often experience a delay in the timing of this afternoon lull as well. As a result, they may not feel sleepy until several hours later.
Easing Post-Meal Drowsiness
While you may not be able to avoid it entirely, there are some things you can try to counteract the sleepiness that occurs after meals:
Eat well-balanced meals. Avoiding meals heavy in carbohydrates or proteins can help you avoid increases in blood sugar (and subsequent crashes) and maintain adenosine levels. Get more nighttime sleep. If you experience sleep deprivation, this after-lunch sleepiness can be more pronounced. In addition, sleep disorders such as obstructive sleep apnea may make this worse. Expose yourself to enough daylight. Circadian rhythms are impacted by sunlight. Our bodies are more alert when exposed to light, and less alert when it’s dark. Get regular exercise. The impact of exercise on sleep is well known. However, be sure to pay attention to when you exercise. For some, exercising too close to bedtime can make it harder to fall asleep. Nap for 10 to 20 minutes. Sometimes, a post-meal nap is an option. But keep it short; anything longer than 20 minutes or so could impact your ability to sleep at your normal time.
A Word From Verywell
It’s not uncommon to feel sleepy after eating a meal. Fortunately, if you tough it out, this period will pass. Then, as the circadian rhythm revs back up, you will find that you feel more alert again in a matter of hours. This natural pattern occurs typically, even without a cup of coffee or a nap.
