title: Breathing during sleep in menopause: a randomized, controlled, crossover trial with estrogen therapy.
abstract: OBJECTIVE
  To evaluate the prevalence of different types of nocturnal breathing abnormalities in postmenopausal women and the effect of estrogen replacement therapy (ERT) on nocturnal breathing.
  
  
  METHODS
  A prospective, randomized, placebo-controlled, double-blind, crossover study was completed by 62 of 71 recruited healthy women. The first 3-month treatment period with either estrogen or placebo was followed by placebo washout for a month and then by a second treatment period with crossover to either estrogen or placebo. On a night after each treatment period, sleep was monitored with polysomnography, and breathing was assessed with a static-charge-sensitive bed and oximeter. For the respiratory variables, a sample size of 48 subjects was sufficient to give statistical power of 85% with a significance level of P <.05.
  
  
  RESULTS
  The occurrence of obstructive sleep apnea in all women was low (1.6%), but partial upper airway obstruction, manifesting as an increased respiratory resistance pattern, was more common (17.7%). Estrogen replacement therapy decreased the occurrence (P =.047) and frequency (P =.049) of sleep apnea but had no effect on partial upper airway obstruction or arterial oxyhemoglobin saturation.
  
  
  CONCLUSIONS
  Partial upper airway obstruction is the most prevalent form of sleep-disordered breathing, occurring ten times more frequently than sleep apnea in postmenopausal women. Unopposed estrogen replacement therapy has only a minor effect on sleep apnea and has no effect on partial airway obstruction.
authors.affiliation: Department of Obstetrics and Gynecology, Turku University Central Hospital, Turku, Finland. paivi.polo-kantola@tyks.fi
authors.forename: Päivi
authors.initials: P
authors.lastname: Polo-Kantola
authors.forename: Esa
authors.initials: E
authors.lastname: Rauhala
authors.forename: Hans
authors.initials: H
authors.lastname: Helenius
authors.forename: Risto
authors.initials: R
authors.lastname: Erkkola
authors.forename: Kerttu
authors.initials: K
authors.lastname: Irjala
authors.forename: Olli
authors.initials: O
authors.lastname: Polo
mesh_terms: D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D015914:Estrogen Replacement Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D015994:Incidence; D008593:Menopause; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods; D011336:Probability; D011446:Prospective Studies; D012016:Reference Values; D012119:Respiration / Q000187:drug effects*; D012307:Risk Factors; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D012891:Sleep Apnea Syndromes / Q000175:diagnosis* / Q000453:epidemiology; D012893:Sleep Wake Disorders / Q000175:diagnosis / Q000453:epidemiology