The straightforward answer is yes. The food we eat is digested into its various elements, e.g. water, glucose, amino acids, and crosses the blood-brain barrier to supply our brains with the nutrients it needs. However, I suspect that is not the question that you are concerned about.
The drowsiness you experience after taking a heavy meal, especially one with a lot of carbohydrates and sugars, is also known as post prandial drowsiness. This is due to the effect of the insulin produced by the body to absorb the sugars in the meal. This is effect is common in most people.
Coupled with your complaints of reflux, I would advise you to take regular smaller meals, instead of infrequent large meals, to avoid both the acid reflux and post prandial effects experienced. It would also help if you do not recline or lie down for at least 45 mins after each meal.
As always, if this does not help, please see your physician for a more detailed consultation. Hope this helps.
