The orexin system and why we snooze after lunch.
I hadn't come across this hormonal system before (it was only discovered in rats around 1998) but it sounds very interesting.
More at http://en.wikipedia.org/wiki/Orexin.
Â» Why Sugar Makes Us Sleepy (And Protein Wakes Us Up)
Sugar subdues neurons in the brain that regulate wakefulness, and protein amps them up. Mixing both sugar and protein, however, leads to surprising results. Frontal Cortex blogger Jonah Lehrer explain…