A Study of Sleep Problems in Undergraduates using Pittsburgh Sleep Quality Index

Abstract

Objective: The purpose of this study was to investigate sleep problems in undergraduates using Pittsburgh Sleep Quality Index (PSQI). Method: One thousand and one hundred eighteen undergraduates (Valid response rate: 84.50%) completed PSQI Japanese version. We analyzed 1092 undergraduates' PSQI data except for those who are using of sleeping medication (n=26: 2.3% of valid responder). Results: (a) Characteristics of PSQI data: As for undergraduates of the current study, C3 (sleep duration), C5 (sleep disturbance) and C7 (daytime dysfunction) and Global PSQI Score were higher and C4 (habitual sleep efficiency) was lower than those of participants at development and validation point in time of PSQI. (b) Sex differences: Compared with female, sleep onset time [t (1083.10)=2.27, p<0.01] and wake time [t (1068.71)=5.82, p<0.01] in male were more delayed. Similarly, total sleep time [t (1090)=4.10, p<0.01] and sleep onset latency [t (1090)=1.70, p<0.10] in male were longer than that in female. As for each PSQI component score, PSQI C2 score of men was significantly higher than that of women [t (1090)=2.19, p<0.05], however C5 [t (1075.10)=-1.83, p<0.10] and C7 [t (1075.10)=-3.72, p<0.01] scores were lower. (c) School grade differences: As a result of one-way ANOVA and post-hoc Scheffe, significant grade differences in sleep onset time [F (3,1088)=7.53, p<0.01, 1st<2nd, 3rd<4th] and wake time [F (3,1088)=7.46, p<0.01, 1st<2nd<3rd,4th] were confirmed. (d) Classification of sleep problems: Hierarchical cluster analysis (ward method) revealed five types of sleep problems: cluster 1 "Short Sleep & Sleep Maintaining Insomnia" (n=238, 21.79%); cluster 2 "Long Sleep & Sleep Maintaining Insomnia" (n=335: 30.68%); cluster 3 "Good Sleep" (n=127, 11.63%); cluster 4 "Sleep Onset Insomnia" (n=156, 14.29%) cluster 5 "Short Sleep Only" (n=236, 21.61%). As a result of one-way ANOVA [F (4,1087)=296.71, p<0.01] and post-hoc Scheffe, "Sleep Onset Insomnia" was the highest global PSQI score of these 5 clusters. Conclusion: Most of undergraduates are poor sleepers, and they have a tendency to insufficient sleep syndrome or circadian sleep rhythm disorder, especially delayed sleep phase syndrome. The sleep phase of juniors and seniors is more delayed than that of freshmen and sophomores. And the symptom of sleep onset insomnia contributes to multidimensional sleep quality in university students. Therefore it is needed to (a) widely inform undergraduates about the importance of regularized sleep-wake rhythms and prolonged sleep time and (b) perform screening test and support students with sleep onset insomnia.