More than a quarter of a century later , scientists at the University of Washington in the United States undertook systematic studies of this phenomenon. They asked many people to rate various life events in terms of the amount of readjustment required. Ultimately, the researchers developed a scale of “Life Change Units” associated with each event. According to this scale, most people feel that the death of a spouse is about twice as stressful as getting married , and five times as stressful as changing to a new school and that stress is associated with positive, happy events as well as with negative and sad events.
Once the scale was developed, it was a fairly simple matter to have people check off the events that applied to them for the last year or so, and then see whether people with high life change scores developed more diseases than people with lower scores. And, in fact, they did. For example, in one study, about 2,500 crew members of several U.S. Navy cruisers were asked to fill out life history forms before they went to sea. Their medical records were examined at the end of a six month cruise. Sailors with life change scores of 88 or less for the six months preceding the cruise had about 7.7 illnesses per 1,000 men per day. The corresponding figure for men with life change scores of 300 above was 9.9. Those with intermediate life change scores had intermediate illness rates. Virtually all of the illnesses reported were relatively minor complaints that are not directly caused by stress. It is not a case of people getting sick if and only if they lead stressful lives. But when stress increases, so does the likelihood of getting sick.