Just one bad night’s sleep makes it more likely that employees who displayed unwanted behaviour one day at work will display a similar type of behaviour the following day. For a study by Rotterdam School of Management, a group of working professionals was asked to indicate how well they had slept each day for ten consecutive working days. They were also invited to rate the extent to which they engaged in unwanted behaviour. For example, had they taken a longer lunch break than allowed that day, or had they been rude towards a co-worker?