Which Parts of a Meal Can Make You Sleepy? (Keith Murphy Interview)

Everyone knows what it’s like to feel sleepy after a big meal. Think of what happens after Thanksgiving dinner, or after getting a huge lunch at an Indian buffet. If you’re like me, you’re ready to crash.

But why does this happen? Is it the tryptophan in the turkey? Is it from too many carbs? What you eat, how much you eat, and when you eat it all play a role. Consequently, there has been some doubt as to whether the “food coma” is even a real thing.

But recently, some clever researchers identified a good model organism for studying this phenomenon — the fruit fly. And through studying the behavior of Drosophila, we now better understand what causes a food coma, and perhaps why it occurs.

Guest

In the newest installment of humanOS Radio, I interview Keith Murphy, a graduate student working in the Ja Lab, at the Scripps Research Institute in Florida. He and his colleagues at Scripps have developed novel systems to track both sleep and food consumption patterns in fruit flies.

In a recent study, they noticed that fruit flies also sleep longer following big meals — much like humans do. They were interested in whether the components of the meal influenced the effect. To test this, they gave the flies food with varying amounts of salt, protein, and sugar to gauge the effects of different nutrients. Perhaps surprisingly, only protein and salt were found to precipitate the post-meal sleep. Interestingly, sugar had no discernible impact here.

So what’s going on? The researchers employed genetic tools to switch neurons on and off in the brains of the flies (one reason why fruit flies are such a handy model compared to humans). They revealed that the response is actually regulated by specific circuits in the brain, which we discuss in greater detail in the interview. It’s worth pointing out that the systems that play a role in post-meal sleepiness are conserved across a wide range of different species meaning that this is likely relevant to other animals, including humans.

Sleep is obviously a vulnerable state for animals in natural environments, leaving them at the mercy of lurking predators and the elements (which is part of what makes sleep so fascinating). The very fact that brain circuits drive animals to sleep after eating suggests that it is important for some physiological purpose. Professor Ja, Keith, and the researchers in the lab have some hypotheses, and are striving now to figure it out.

Listen above to learn more about Keith’s intriguing study, and what it might mean for our own sleeping and eating patterns.