title: Day length and weather effects on children's physical activity and participation in play, sports, and active travel.
abstract: BACKGROUND
  Children in primary school are more physically active in the spring/summer. Little is known about the relative contributions of day length and weather, however, or about the underlying behavioral mediators.
  
  
  METHODS
  325 British children aged 8 to 11 wore accelerometers as an objective measure of physical activity, measured in terms of mean activity counts. Children simultaneously completed diaries in which we identified episodes of out-of-home play, structured sports, and active travel. Our main exposure measures were day length, temperature, rainfall, cloud cover, and wind speed.
  
  
  RESULTS
  Overall physical activity was higher on long days (≥ 14 hours daylight), but there was no difference between short (< 9.5 hours) and medium days (10.2-12.6 hours). The effect of long day length was largest between 5 PM and 8 PM, and persisted after adjusting for rainfall, cloud cover, and wind. Up to half this effect was explained by a greater duration and intensity of out-of-home play on long days; structured sports and active travel were less affected by day length.
  
  
  CONCLUSIONS
  At least above a certain threshold, longer afternoon/evening daylight may have a causal role in increasing child physical activity. This strengthens the public health arguments for daylight saving measures such as those recently under consideration in Britain.
authors: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors: Anna
authors: A
authors: Goodman
authors: James
authors: J
authors: Paskins
authors: Roger
authors: R
authors: Mackett
mesh_terms: D061725:Accelerometry; D002648:Child; D004739:England; D015444:Exercise; D006801:Humans; D017440:Photoperiod; D010988:Play and Playthings; D011634:Public Health; D012621:Seasons; D013177:Sports; D014887:Weather