(MENAFN - The Conversation) Do financial traders make better returns in the stock market when they are well rested? You would intuitively assume that a trader's level of sleep would affect their decision making. Several studies have certainly shown that sleep affects the ability of people to make decisions in general. Though admittedly based on small samples of participants, these studies show that those who are short on sleep tend to have relatively low attention to detail, poor memory, poor performance and significant mood swings. But when it comes to whether sleep affects financial decisions, the evidence has been mixed. The only measure of sleepiness that has been used is the annual clock changes for daylight saving that take place in many countries , since they disturb many people's sleep. A few studies have used this to look at how stock market returns are affected on the Mondays directly after the clocks go back or forward by an hour.