Lost sleep is costing the average American worker 11.3 days in lost productivity each year, meaning the total cost of poor rest to the country as a whole is a whopping $63.2 billion (£39 billion) annually, according to a new study. Following a study of 7,428 workers in the Harvard Medical School's American Insomnia Study survey of 2008-09, it was found that around 23.2 per cent of participants had insomnia. Rates were lower for workers age 65 and above (14.3 per cent) and were less of a problem for working men (19.7 per cent) than women (27.1 per cent). The study's researchers also found that insomnia rates were 19.9 per cent for those who did not complete their high school education, whereas it stood at 21.5 per cent for college graduates. Funded by Merck & Co, which is developing a new sleeping pill, the paper was published in the September 1st edition of the journal Sleep. Lead author Ronald C. Kessler said: "It's an underappreciated problem. Americans are not missing work because of insomnia. They are still going to their jobs but accomplishing less because they're tired. In an information-based economy, it's difficult to find a condition that has a greater effect on productivity."