Medically reviewed by Johnstone M. Kim, MD Key Takeaways The pupil controls how much light enters the eye, allowing for clear ...

The iris is a structure behind the transparent cornea of the eye. It has a circular opening called the pupil that changes size in response to the light level. Your pupils are usually the same size as ...

New research suggests that two simple, quantifiable measures -- spontaneous fluctuations in pupil dilation or heart rate -- could enable earlier diagnosis of Rett syndrome and possibly other disorders ...

Arousal is a fundamental part of how our brain keeps us alert, engaged, and responsive to the world around us. It is controlled by networks deep in the brainstem, like the locus coeruleus (LC), which ...

Fatigue plays a crucial role in safeguarding against overexertion by inducing feelings of tiredness and causing temporary reductions in physical and mental performance. However, according to a recent ...

Pupillometry, the measurement of pupil size and its dynamic changes in response to light, cognitive load and emotional stimuli, has emerged as a non-invasive window into autonomic and neuromodulatory ...

Fatigue plays a crucial role in safeguarding against overexertion by inducing feelings of tiredness and causing temporary reductions in physical and mental performance. However, according to a recent ...