Sugar may give you a high, but protein is what really can keep you awake, new research suggests.

The stomach digests food, but the brain interprets the complex mixture of nutrients that tells a person when to eat, what to eat and how much to eat.

Researchers previously knew how the brain regulated individual nutrients, such as sugar and proteins, but people eat real food that contains an assortment of nutrients. How the brain interprets these combinations is beginning to become uncovered in research released Thursday in the journal Neuron.

Scientists monitored a group of neurons called orexin/hypocretin that regulate wakefulness and energy in people. When people eat sugar, these neurons get shut down, known best as the sugar crash that happens after a candy high.

However, when researchers added amino acids, the basic building blocks of proteins, into the sugary mix, the neurons became activated. In other words, protein overcame the inhibitory effect of sugar in the neurons.

Our data support the idea that the orexin/hypocretin neurons are under a 'push-pull' control by sugars and proteins, Denis Burdakov, pharmacology researcher at the University of Cambridge, said in a statement. Interestingly, although behavioral effects are beyond the scope of our study, this cellular model is consistent with reports that when compared with sugar-rich meals, protein-rich meals are more effective at promoting wakefulness and arousal.

The research suggests that a diet focused on regulating single nutrients may miss the complexities of how the body interprets food.

We found that activity in the orexin/hypocretin system is regulated by macronutrient balance rather than simply by the caloric content of the diet, suggesting that the brain contains not only energy-sensing cells, but also cells that can measure dietary balance, Burdakov stated.