Natural evolution of sleepiness. A 5-year follow-up study in a middle-aged population

The prevalence and natural evolution of sleepiness were investigated in a 5-year follow-up study in a middle-aged population in Finland. In the original study a structured sleep questionnaire was completed by 1190 subjects and a 5-year follow-up questionnaire was returned by 626. The prevalence of sleepiness, meaning here an unintentional tendency to fall asleep weekly in the course of everyday living, was 9.6% in the first survey and 10.6% 5 years later in the same cohort; 3.7% had been sleepy in both surveys. Sleep fragmentation, leg jerking and awakenings during sleep were common findings among sleepy subjects in both surveys. Shift-workers and those who had irregular working hours ran a risk of chronic sleepiness. Sleepiness was also associated with poor subjective health, obesity, depression, nervousness and tension. In particular, chronically sleepy subjects had an increased risk of sleepiness-related traffic accidents and premature retirement. Contrary to common findings from sleep laboratories, neither snoring nor self- or spouse-reported breathing pauses during sleep were significantly associated with long-term sleepiness in a non-selected middle-aged population. It is suggested that more attention should be paid to subjects suffering from excessive daytime sleepiness even if they do not have a history of respiratory or other known organic sleep disorder. Eur J Neurol 5:355-363 (C) 1998 Lippincott-Raven Publishers.