Orexin or hypocretin is a peptide released by neurons, which is responsible for maintaining wakefulness.
The cells producing orexin are also present in different brain regions, including hypothalamus, which is partly responsible for maintaining the awakening state.
Mice without orexin producing cells fall into catalepsy during the active states such as feeding. These results support the idea that orexin is necessary to maintain the normal state of wakefulness.