Napping and associated factors: a Japanese nationwide general population survey.
The objective of this study was to investigate napping habits and their associated factors in the Japanese adult general population.



The cross-sectional survey was conducted in November 2007 for subjects selected randomly from among 300 districts throughout Japan. Data from 7664 people (3527 men and 4137 women), aged 20-99 years, were analyzed. Participants completed a self-administered questionnaire on frequency and duration of napping.



The percentage of responders for high-frequency napping, four or more days per week, was 21.2% among men and 17.1% among women. The percentage of responders for long-duration napping, 2 h or more per one nap, was 2.9% among men and 2.6% among women. Multivariate logistic regression analyses revealed that men, older age, smoking, insomnia symptoms, long sleep duration, excessive daytime sleepiness, and having sufficient rest obtained by sleep were positively associated with high-frequency napping, whereas alcohol drinking showed a negative association. Older age was negatively associated with long-duration napping whereas living in a large community, smoking, long sleep duration, excessive daytime sleepiness, and psychological stress showed a positive association.



These findings provide important data for future studies aimed at improvement of sleep habits.
Department of Psychiatry, Nihon University School of Medicine, Tokyo, Japan.
Ryuji
R
Furihata
Department of Public Health and Epidemiology, Faculty of Medicine, Oita University, Oita, Japan. Electronic address: kaneita.yoshitaka@gmail.com.
Yoshitaka
Y
Kaneita
Division of Public Health, Department of Social Medicine, Nihon University School of Medicine, Tokyo, Japan.
Maki
M
Jike
Division of Public Health, Department of Social Medicine, Nihon University School of Medicine, Tokyo, Japan.
Takashi
T
Ohida
Department of Psychiatry, Nihon University School of Medicine, Tokyo, Japan.
Makoto
M
Uchiyama
D000328:Adult; D000368:Aged; D000428:Alcohol Drinking; D044466:Asian People; D003430:Cross-Sectional Studies; D006970:Disorders of Excessive Somnolence / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006184:Habits; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D011159:Population Surveillance; D015995:Prevalence; D007319:Sleep Initiation and Maintenance Disorders; D011795:Surveys and Questionnaires
Epidemiology; Excessive daytime sleepiness; Insomnia; Japan; Napping; Siesta