Is there a molecule in Turkey that makes me feel tired?

Around the winter holidays, many families gather around the dining table to enjoy a nice turkey meal. A common belief is that turkey meat can make people feel tired. But is this true? 
 
While turkey meat does contain serotonin (a brain chemical involved with sleep), the amount is very small! This means that even if you ate a lot of turkey meat, this cannot cause sleepiness. So why might you feel tired? 
 
Well, that might be because of the amount of food you’re eating. As we eat more, our stomachs expand and release molecules that tell our brains to stop. Researchers have found that one side effect of this is the feeling of fatigue. 
 
So, next time you feel tired at dinner, please know that it’s not the turkey’s fault!