Bipolar Disorder costs U.S. businesses twice as much in lost productivity than major depression, a new study finds. Each U.S. worker with bipolar disorder averages 65.5 lost workdays a year, compared to 27.2 annual lost work days for those with depression.

Overall, major depression is six times more common than bipolar disorder, but bipolar disorder costs U.S. businesses nearly half as much as major depression, at more than $14 billion a year, the study said.

The findings are based on a year of data collected from nearly 3,400 workers who took part in a national survey. Workers were asked how many days in the previous year they had experienced a mood-disorder episode. Lost productivity was calculated by combining work days lost due to absence or poor functioning on the job and salary data.

About one percent of U.S. workers experience bipolar disorder in a year, compared to 6.4 percent who battle major depression. However, the researchers estimated that bipolar disorder accounts for 96.2 million lost workdays a year and $14.1 billion in lost salary/lost production, compared to 225 million lost workdays and $36.6 billon in lost salary/lost production for major depression.