Fig. 2From: Changes in self-reported sleep duration with age - a 36-year longitudinal study of Finnish adultsKaplan-Meier estimates of sleep duration in the four points of measurement. X-axis: sleep duration in hours. Y-axis: proportion of respondents with a certain sleep duration; e.g. in 1975 90% of the respondents slept 6 h or more, and 60% 7 h or moreBack to article page