Protein and Salt Cause Afternoon Sleepiness

Depending on what you ate over the holidays, there's a good chance you're well acquainted with something scientists at The Scripps Research Institute have been researching. That's because they've been studying so-called "food comas." Many of us experience these after a big celebratory meal. So these researchers wanted to find out just what types of food cause us to feel so lethargic after a feast. And what they found gives you some suggestions for feeling great after you eat – and not so tired.

The researchers started by using fruit flies as their test subjects. It's a lot easier to map the neural activities in flies' brains than in humans'. And the connection between metabolism and sleep (yes, fruit flies do sleep) in flies is already well-understood.

The researchers wanted to determine if specific nutrients would affect how much the flies slept. So they tested out protein, salt, and sugar. Of the three, both protein and salt caused an increase in sleep. So the flies that ate the most also slept the most.

Continued Below...

Despite the simplicity of the fruit flies' brains, the researchers were surprised to find that several circuits were involved in the post-meal sleep process. They were able to identify that a particular type of neuron (leucokinin) that's known to play a role in regulating meal size also affects sleep after a meal. They also found that other brain circuits related to the flies' internal clocks helped them be less sleepy after a meal around dusk.

The researchers plan to continue investigating the roles brain circuitry and different types of food play in promoting sleepiness after a meal. In the meantime, obviously, consider quantity — excess = sleepiness. And if you'd like to conduct your own experiment, try keeping your mid-day meals well-balanced with different vegetables in addition to some protein and salt to taste and no more. You'll feel a lot more energetic after you eat than you might expect!

And if you do happen to have a larger meal at lunch with simply too much food, consider oolong or green tea along with your meal or after as a desert. Oolong aids in the digestion of the fat, and both oolong and green tea provide a small amount of caffeine to keep you alert as you go about the rest of your day.

Janet Zand

Sources:

Keith R Murphy, Sonali A Deshpande, Maria E Yurgel, James P Quinn, Jennifer L Weissbach, Alex C Keene, Ken Dawson-Scully, Robert Huber, Seth M Tomchik, William W Ja. Postprandial sleep mechanics in Drosophila. eLife, 2016; 5 DOI: 10.7554/eLife.19334