With additional controls, the Stanford group proved that the release of orexin from the lateral hypothalamus was what drove this behavior. (scientificamerican.com)
Eating lots of sugar reduces the activity of what are called orexin cells. (sleep.org)
It's also been shown that amino acids, such as those found in meat, have the ability to simulate orexin cells which would make you feel more alert and awake. (mindbodygreen.com)