Fruit flies sleeping (IMAGE) Northwestern University Caption Flies are pre-programmed to take a midday siesta. Credit Please credit image to Gallio Lab/Northwestern University Usage Restrictions Please credit image to Gallio Lab/Northwestern University License Original content 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.