Pupil Size and Sleep (image) Cell Press Share Print E-Mail Caption This is an artistic illustration of how mouse pupil size is a window into brain activity even during sleep. Credit Daniel Huber, University of Geneva. Usage Restrictions Credit Required. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.