Daytime sleepiness: A risk factor for poor social engagement among the elderly Author:Publication type: Journal ArticleYear: 2013InterRAI Authors: Lee, Y. T.Tsai, C. F.Ouyang, W. C.Yang, A. C.Yang, C. H.Hwang, J. P.Journal/Series title: PsychogeriatricsVolume number: 13Issue: 4Pages: 213-220