Previous studies have shown that simple carbohydrates, such as glucose, lower the activity of cells involved in wakefulness and energy use. Denis Burdakov, from the University of Cambridge (United Kingdom), and colleagues conducted a lab animal study in which they tracked the responsiveness of orexin neurons, when exposed to amino acids – the building blocks of protein. The team found that amino acids stimulated greater orexin cell activity, and prevented glucose from inhibiting the same activity. As a result, improve wakefulness and energy use resulted.  The study authors conclude that: " These results suggest a new mechanism of hypothalamic integration of macronutrient signals and imply that orexin/hypocretin] cells sense macronutrient balance, rather than net energy value, in extracellular fluid.”