title: Relationship between daily isoflavone intake and sleep in Japanese adults: a cross-sectional study.
abstract: BACKGROUND
  Isoflavones comprise a class of phytoestrogens that resemble human estrogen in chemical structure, and have weak estrogenic effects. Because estrogen modulates sleep duration and quality, we hypothesized that isoflavones would have a beneficial effect on sleep status in a way similar to estrogen. We conducted a cross-sectional study to investigate the relationship between daily isoflavone intake and sleep status in Japanese subjects.
  
  
  METHODS
  Our study included 1076 Japanese adults aged 20-78 years. Daily isoflavone intake was assessed using a brief self-administered diet history questionnaire, and sleep was evaluated using a self-reported questionnaire.
  
  
  RESULTS
  The prevalence of regular sleep duration (7-8 h/day) and sufficient sleep quality were 13.3% and 56.2%, respectively. After adjusting for potential confounding factors, the odds ratios (95% CIs) for optimal sleep duration (7-8 h) when higher isoflavone intakes (Q2-Q4) were compared with low isoflavone intake (Q1) were Q2: 0.94 (0.53-1.56); Q3: 1.28 (0.73-2.24); and Q4: 1.84 (1.06-3.18) (p for trend = 0.013). In the final adjusted model, sufficient sleep quality across categories of isoflavone intake was Q1: 1.00 (reference); Q2: 1.30 (0.91-1.84); Q3: 1.48 (1.03-2.12); and Q4: 1.78 (1.22-2.60); (p for trend = 0.002).
  
  
  CONCLUSIONS
  Higher daily isoflavone intake was positively associated with optimal sleep duration and quality in a Japanese population. This finding suggests that daily isoflavone intake may have a potentially beneficial effect on sleep status.
authors.affiliation: Division of Biomedical Engineering for Health & Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan. bigshowgod@yahoo.co.jp.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Department of Epidemiology, School of Public Health, Tianjin Medical University, Heping District, Tianjin, People's Republic of China. nkj0809@gmail.com.
authors.forename: Kaijun
authors.initials: K
authors.lastname: Niu
authors.affiliation: Division of Biomedical Engineering for Health & Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan. hcongman@yahoo.com.
authors.forename: Cong
authors.initials: C
authors.lastname: Huang
authors.affiliation: Division of Biomedical Engineering for Health & Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan. harupiyo326@hotmail.com.
authors.forename: Haruki
authors.initials: H
authors.lastname: Momma
authors.affiliation: Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai, Japan. guanlei09@hotmail.co.jp.
authors.forename: Lei
authors.initials: L
authors.lastname: Guan
authors.affiliation: Division of Biomedical Engineering for Health & Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan. y-kobayashi@m.tains.tohoku.ac.jp.
authors.forename: Yoritoshi
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Tianjin University of Sport, Tianjin, China. jpkakuki@yahoo.co.jp.
authors.forename: Hui
authors.initials: H
authors.lastname: Guo
authors.affiliation: Division of Biomedical Engineering for Health & Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan. chuziyou.masahiko@xu31.fks.ed.jp.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Chujo
authors.affiliation: Division of Biomedical Engineering for Health & Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan. ootomo@itamitoru.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Otomo
authors.affiliation: Division of Biomedical Engineering for Health & Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan. nagatomi@med.tohoku.ac.jp.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Nagatomi
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004032:Diet / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012890:Sleep; D012893:Sleep Wake Disorders / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D007529:Isoflavones