title: Advanced sleep-wake rhythm in adults born prematurely: confirmation by actigraphy-based assessment in the Helsinki Study of Very Low Birth Weight Adults.
abstract: OBJECTIVE
  Previous studies have suggested a propensity towards morningness in teenagers and adults born preterm. We set out to study sleep in a subsample from The Helsinki Study of Very Low Birth Weight Adults cohort, with emphasis on sleep timing, duration, and quality. We compared young adults who were born prematurely at very low birth weight (VLBW; <1500 g) with controls born at term.
  
  
  METHODS
  We measured sleep by actigraphy in young adults aged 21-29 years. A total of 75 individuals (40 VLBW and 35 controls) provided adequate data. Group differences in sleep parameters were analyzed using t-test and linear regression models.
  
  
  RESULTS
  VLBW adults woke up on average 40 min earlier [95% confidence interval (CI), 9-70] and reported 40 min earlier get up time (95% CI, 8-71) than did the controls. The difference remained after adjustment for confounders. We found no group difference in sleep duration or measures of sleep quality.
  
  
  CONCLUSIONS
  Our findings of earlier rising in the VLBW group are suggestive of an advanced sleep phase in that group. These results reinforce previous suggestions that chronotype may be programmed early during life.
authors: Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland; National Institute for Health and Welfare, Helsinki, Finland. Electronic address: johan.bjorkqvist@helsinki.fi.
authors: Johan
authors: J
authors: Björkqvist
authors: Child Psychiatry, Helsinki and Uusimaa Hospital District, Helsinki, Finland; National Institute for Health and Welfare, Helsinki, Finland.
authors: Juulia
authors: J
authors: Paavonen
authors: Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
authors: Sture
authors: S
authors: Andersson
authors: Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland.
authors: Anu-Katriina
authors: AK
authors: Pesonen
authors: Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland.
authors: Jari
authors: J
authors: Lahti
authors: Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland.
authors: Kati
authors: K
authors: Heinonen
authors: National Institute for Health and Welfare, Helsinki, Finland; Department of General Practice and Primary Health Care, University of Helsinki, Helsinki, Finland; Vasa Central Hospital, Vasa, Finland; Unit of General Practice, Helsinki, Finland; Folkhälsan Research Centre, Helsinki, Finland.
authors: Johan
authors: J
authors: Eriksson
authors: Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland.
authors: Katri
authors: K
authors: Räikkönen
authors: Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland; National Institute for Health and Welfare, Helsinki, Finland.
authors: Petteri
authors: P
authors: Hovi
authors: Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland; National Institute for Health and Welfare, Helsinki, Finland.
authors: Eero
authors: E
authors: Kajantie
authors: Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland; National Institute for Health and Welfare, Helsinki, Finland.
authors: Sonja
authors: S
authors: Strang-Karlsson
mesh_terms: D056044:Actigraphy; D000328:Adult; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005387:Finland; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000175:diagnosis* / Q000453:epidemiology; D007236:Infant, Small for Gestational Age; D019102:Infant, Very Low Birth Weight; D008297:Male; D020178:Sleep Disorders, Circadian Rhythm / Q000175:diagnosis* / Q000453:epidemiology; D055815:Young Adult
keywords: Actigraphy; Chronotype; Morningness; Prematurity; Sleep; Very low birth weight