Self-report sleep habits as predictors of subjective sleepiness.

Although sleepiness is pervasive in our society, there is little agreement on how to measure sleepiness or on how well sleepiness is actually related to sleep habits. To better assess how subjective sleepiness is related to sleep, the authors used self-report measures of sleep quantity, sleep quality, and napping to predict 4 different sleepiness-related measures in a group of healthy young and middle-aged-to-older adults. A forward regression analysis indicated that sleep quality was better than sleep quantity as a predictor of participants' sleepiness. The sleep measures, furthermore, predicted sleepiness better in the older adults than in the younger adults. Finally, the 4 sleepiness measures differed in how well they were related to sleep. The findings in the study suggest that sleepiness is a complex phenomenon rather than a simple reflection of sleep quantity.