The Lundby study is a prospective, epidemiological survey of mental he
alth in a total population. When evaluating the material of 2550 indiv
iduals followed from 1947 to 1972, we found a large group with mental
tiredness as the dominating symptom. Next to depression this was the m
ost frequent diagnosis in the population. According to our concept of
Tiredness, one third of the women ran a lifetime risk of developing a
first-ever episode of Tiredness, while the risk for men was one fifth.
The incidence of Tiredness is described together with the total frequ
ency of episodes. The course of mental illness starting with a first e
pisode of Tiredness within the 25-year investigation period shows that
about one third of the men and half of the women relapsed into Tiredn
ess or other mental illnesses, not infrequently with a serious outcome
. However, most of the episodes of Tiredness lasted less than 2 years
and were of milder impairment. We emphasize the importance of further
investigations by means of epidemiological, clinical and neurochemical
methods as regards the heterogeneous syndrome of mental fatigue.