Over time a person may suffer more frequent (more rapid-cycling) and more severe manic and depressive episodes than those experienced when the illness first appeared.4but.
Social and economic conditions and their effects on people's lives determine their risk of illness and the actions taken to prevent them becoming ill or treat illness when it occurs.
For instance, the Ladies Friends of Faith Benevolent Association, a black-female society, would pay members taken ill $2 a week if they saw the lodge doctor, and $3 if they didn't.
But recent studies suggest that noise could even be dangerous, increasing stress levels and risk of illness - the word "noise" does derive from the Latin "nausea" after all.
Conflict too brings health crises, as devastated and displaced populations lose contact with medical services and experience increased vulnerability and trauma.
A study in Sweden indicated that kindergarten children who could play in a natural environment had less illness and greater physical ability than children used only to a normal playground.