Construction of Sleep-Hygiene Scales and Classification of Sleep Patterns in Undergraduates

Insufficient sleep affects mood and behavior, and, in students, may lead to secondary problems at school such as performance failures and lapses. In order to consider the possibility of preventing sleep disorders, we constructed 3 scales to examine the sleep hygiene of undergraduates. Varimax factor analyses performed on the data from 2347 undergraduates resulted in the extraction of 3 internally consistent (PCA) factors: a Phase-related factor (“regular-irregular sleeper,” and “morningness-eveningness”); a Qualityrelated factor (“good-poor sleeper”); and a Quantity-related factor (“long-short sleeper”). Cluster analysis was performed based on the first principal component score in each scale. We then classified the students into 6 groups, based on their sleep-habit profile on the 3 factors. 4 of the 6 groups obtained by this analysis showed sleep problems that could be interpreted as potential sleep disorders defined by standard diagnostic criteria, such as Insufficient sleep syndrome, Sleep state misperception, and Circadian rhythm disorders. Such undesirable sleep hygiene in undergraduates might cause sleep disorders later in their lives. The results also revealed a significant gender difference in sleep patterns. The relation of biological factors to sleep patterns was also discussed.