In a prospective study of 3877 males, aged 39-65 years, the hypothesis was tested that sleep complaints are predictive of myocardial infarction. It was found that complaints about troubles in falling asleep and about feeling exhausted when one wakes up were predictive of myocardial infarction occurring in a 4.2 years follow-up period. However, this predictive power was confounded by age, and especially by vital exhaustion. It is concluded that sleep complaints are long term determinants of myocardial infarction because they are part of the syndrome of vital exhaustion.