A questionnaire was sent out to a randomly selected, age (20-34, 35-49, and 50-64 years) and sex stratified sample of 600 adult inhabitants in Uppsala County, Sweden. Overall response rate was 68%. The questionnaire comprised questions about sleep and sleep complaints. Subjects were also asked to rate the degree of a number of proposed causes and consequences of insufficient sleep, in accordance with how they had perceived them when they had experienced insufficient sleep. Results showed that twelve percent of the total sample fulfilled the criteria for persistent insufficient sleep (PIS), an operationally defined condition of considerable chronic sleep loss. One-half of these subjects also reported concomitant sleeping difficulties. In subjects with PIS without sleeping difficulties, the most conspicuous causes of insufficient sleep were work-related factors and simply too little time for sleep. As for the effects of insufficient sleep in subjects with PIS with concomitant sleep complaints, factors relating to somatic symptoms, dysphoric mood and impaired cognition were the most prominent, while dysphoric mood was most noticeable in subjects with PIS without sleep complaints.