Sleepiness After Eating Lunch

As you return to your work after eating lunch, you may wonder: Why am I so sleepy in the afternoons? You may wonder if it has something to do with what you ate for lunch or if something else is the culprit.

Well, it may relate to a natural dip in the alerting signal of the circadian rhythm. This article explains some theories about post-lunch sleepiness and offers some ideas for staying alert in the afternoon.

Businesswoman, yawned she was tired of working in an office.
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Digestion

It is natural to feel a little sleepy after eating lunch. However, since sleepiness occurs right after people eat, some mistakenly think that it relates to digestion.

In particular, there is a misconception about how blood flow from the brain to the stomach during digestion might cause sleepiness. Although this sounds plausible, it doesn't make that much sense.

If this were the case, you'd expect to feel just as sleepy after eating a large breakfast or after dinner. However, the truth is that this sleepiness is unrelated to the process of digestion.

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 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.

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.

Most people naturally feel sleepy between 1 p.m. and 3 p.m.

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-Lunch Drowsiness

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.

Here are some things you can try to counteract the sleepiness that occurs in the early afternoon:

  • Get more nighttime sleep
  • Expose yourself to enough daylight
  • Get regular exercise
  • Caffeine in moderation
  • Nap for 10 to 20 minutes

Each of these can reduce the adenosine levels that contribute to sleepiness.

A Word From Verywell

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.

Frequently Asked Questions

  • Are there certain foods that make you sleepy?

    Yes, there are certain foods and drinks that can make you sleepy, or at least reduce alertness. Some of these include kiwi, tart cherries or sour cherries, malted milk, fatty fish like salmon, walnuts, rice, and certain varieties of red grapes. In multiple studies, eating a moderate amount of these foods show a link to better sleep. Foods that are rich with carbohydrates are also known to induce fatigue.

  • What should I eat if I feel tired during the day?

    If you feel tired during the day, it may help to eat a small amount of fruit and nuts to give your brain a boost. Eating smaller, healthy meals during the day instead of a big lunch can also reduce tiredness. Staying hydrated by drinking water regularly may also help avoid feeling tired as easily.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Paredes SD, Barriga C, Reiter RJ, Rodríguez AB. Assessment of the potential role of tryptophan as the precursor of serotonin and melatonin for the aged sleep-wake cycle and immune function: Streptopelia Risoria as a model. Int J Tryptophan Res. 2009;2:23–36. doi:10.4137/ijtr.s1129

  2. Harvard School of Medicine, Healthy Sleep: External Factors That Influence Sleep.

  3. Sleep Foundation. The Best Foods to Help You Sleep.

  4. Panossian LA, Veasey SC. Daytime sleepiness in obesity: mechanisms beyond obstructive sleep apnea--a reviewSleep. 2012;35(5):605-615. doi:10.5665/sleep.1812

  5. Harvard Health Publishing: Harvard Medical School. Foods That Fight Fatigue.

Additional Reading
  • Kryger, MH et al. Principles and Practice of Sleep Medicine. Elsevier, 6th edition.

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.