title: Insomnia and endothelial function - the HUNT 3 fitness study.
abstract: BACKGROUND
  Insomnia is associated with increased risk of coronary heart disease (CHD), but the underlying mechanisms are not understood. To our knowledge, no previous studies have examined insomnia in relation to endothelial function, an indicator of preclinical atherosclerosis. Our aim was to assess the association of insomnia with endothelial function in a large population based study of healthy individuals.
  
  
  METHODS
  A total of 4 739 participants free from known cardiovascular or pulmonary diseases, cancer, and sarcoidosis, and who were not using antihypertensive medication were included in the study. They reported how often they had experienced difficulties falling asleep at night, repeated awakenings during the night, early awakenings without being able to go back to sleep, and daytime sleepiness. Endothelial function was measured by flow mediated dilation (FMD) derived from the brachial artery.
  
  
  RESULTS
  We found no consistent association between the insomnia symptoms and endothelial function in multiadjusted models, but individual insomnia symptoms may be related to endothelial function. Among women who reported early awakenings, endothelial function may be lower than in women without this symptom (p = 0.03).
  
  
  CONCLUSIONS
  This study provided no evidence that endothelial function, an early indicator of atherosclerosis, is an important linking factor between insomnia and CHD. Further studies are needed to explore the complex interrelation between sleep and cardiovascular pathology.
authors.affiliation: Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. linn.b.strand@ntnu.no
authors.forename: Linn B
authors.initials: LB
authors.lastname: Strand
authors.forename: Lars E
authors.initials: LE
authors.lastname: Laugsand
authors.forename: Eli-Anne
authors.initials: EA
authors.lastname: Skaug
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Ellingsen
authors.forename: Erik
authors.initials: E
authors.lastname: Madssen
authors.forename: Ulrik
authors.initials: U
authors.lastname: Wisløff
authors.forename: Lars
authors.initials: L
authors.lastname: Vatten
authors.forename: Imre
authors.initials: I
authors.lastname: Janszky
mesh_terms: D000328:Adult; D000368:Aged; D001916:Brachial Artery / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D007319:Sleep Initiation and Maintenance Disorders / Q000503:physiopathology*; D011795:Surveys and Questionnaires