The United Mind poll of 3,000 Swedes, conducted in partnership with newspaper Aftenbladet, found respondents reporting having an average 3.8 sexual encounters per month, down from five when the survey conducted in 1996, The Local.se reported Friday.
The pollster said 60 percent of respondents reported having sex in the past month, down from about 80 percent in the 1996 poll.
"These are serious numbers and seem to be part of an international trend. My colleagues from other countries have found the same thing," said Malmo University sociology Professor Sven-Axel Mansson, who worked on the study in 1996. "They say it's a public health problem. Desire disorder has become a diagnosis."
United Mind did not release its survey methodology or a margin of error for the poll.