title: Children's heart rate variability as stress indicator: association with reported stress and cortisol.
abstract: Stress is a complex phenomenon coordinated by two main neural systems: the hypothalamic-pituitary-adrenal system with cortisol as classical stress biomarker and the autonomic nervous system with heart rate variability (HRV) as recently suggested stress marker. To test low HRV (5 minute measurements) as stress indicator in young children (5-10 y), associations with self-reported chronic stress aspects (events, emotions and problems) (N=334) and salivary cortisol (N=293) were performed. Peer problems, anger, anxiety and sadness were associated with lower root mean square of successive differences (RMSSD) and high frequency power (i.e. lower parasympathetic activity). Anxiety and anger were also related to a higher low frequency to high frequency ratio. Using multilevel modelling, higher cortisol levels, a larger cortisol awakening response and steeper diurnal decline were also associated with these HRV patterns of lower parasympathetic activity.
  
  
  CONCLUSIONS
  Low HRV (lower parasympathetic activity) might serve as stress indicator in children.
authors.affiliation: Department of Public Health, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185, 2 Blok A, B-9000 Ghent, Belgium. Electronic address: nathalie.michels@ugent.be.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Michels
authors.forename: Isabelle
authors.initials: I
authors.lastname: Sioen
authors.forename: Els
authors.initials: E
authors.lastname: Clays
authors.forename: Marc
authors.initials: M
authors.lastname: De Buyzere
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ahrens
authors.forename: Inge
authors.initials: I
authors.lastname: Huybrechts
authors.forename: Barbara
authors.initials: B
authors.lastname: Vanaelst
authors.forename: Stefaan
authors.initials: S
authors.lastname: De Henauw
mesh_terms: D002648:Child; D002675:Child, Preschool; D004644:Emotions / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D016014:Linear Models; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012463:Saliva / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013315:Stress, Psychological / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology; D011795:Surveys and Questionnaires
chemical_list: D006854:Hydrocortisone
keywords: Biomarker; CAR; ChiBS; Children; HF; HRV; Heart rate variability; LF; PA; Questionnaire; RMSSD; SA; Salivary cortisol; Stress; children's body composition and stress; cortisol awakening response; heart rate variability; high frequency; low frequency; normalized units; nu; pNN50; parasympathetic activity; percentage of consecutive normal RR intervals differing more than 50 ms; root mean square of successive differences; sympathetic activity