Orexin's Influence on Pupil Size Revealed

Orexin, not the stress hormone noradrenaline, is responsible for regulating pupil size, challenging previous understanding. Orexin neurons affect pupil size in response to emotional states and mental strain, not just light exposure. This discovery has implications for neurological conditions such as narcolepsy and Alzheimer's, offering new diagnostic avenues. It also sheds light on our understanding of consciousness and attention regulation.