"Long, dark nights are with us now that the clocks have gone back, but they may be held at bay in future years after new research led by the London School of Hygiene & Tropical Medicine suggests that moving the clock forward all year round could be good for health.".
The study - published in the Journal of Physical Activity and Health - found that children were the most physically active on long summer days, with the biggest effect showing between 5pm and 8pm on longer days. Importantly, daylight rather than the weather holds the key, according to the authors, because the effect was strongest in the late afternoon and early evenings, and because it remained constant even when bad weather was taken into account.
A team led by Dr Anna Goodman, NIHR funded Research Fellow at LSHTM, analysed information on the amount of physical activity done by children between the age of eight and 11 across the day, and examined how this pattern differed by day length.
To do this, instruments called accelerometers, which record body movements, were placed around the waists of 325 children in Hertfordshire in their daily routine for a total of 817 days spread over the four seasons.
The highest overall level of activity (mainly outdoor play) was recorded during the long summer days (with 14 or more hours of daylight). The researchers point out that the biggest difference between long days and short or medium days was between 5pm and 8pm which is what would be expected if day light rather than weather were the key factor. In addition the trend remained constant after taking in account bad weather days (rain, cloudy sky and wind).
Dr Goodman says: "The fact that kids spend more time playing outdoors and are more physically active overall on these longer days could be important at a population-level for promoting their fitness and in preventing child obesity. This strengthens the public health argument for the Daylight Saving Bill currently under consideration by the House of Commons, which proposes putting the clocks forward by an extra hour all year round."
Part of the explanation for the increased physical activity on longer days seemed to be the greater amount of time children spent playing. On long days, the children recorded spending 22% of their time taking part in out-of-home play in afternoons and early evenings, while the figure decreased significantly when the day became shorter (13% on medium and short days; 12.6 to 10 hours and less than 9.5 hours respectively). Other activities like organised sports such as football were barely affected by the length of the day.
The research doesn't examine why children spend less time playing outside on short, dark days, but the authors speculate that it may be a combination of children being less keen to play and their parents being less keen to let them.
The authors of the research conclude: "This represents the most direct evidence yet that (at least at some points of the year) redistributing daylight hours to the afternoon might prove an effective population-level intervention to promote child physical activity. In combination with the evidence that such measures would avert road traffic crashes and reduce greenhouse emissions, this study therefore bolsters the public health arguments in favour of daylight saving measures such as those currently under consideration in the UK."
For more information or to interview Dr Goodman please contact the London School of Hygiene & Tropical Medicine Press Office. Paula.fentiman@lshtm.ac.uk or Giorgio.defaveri@lshtm.ac.uk or call 44-207-927-2802
Notes to Editors:
Journal reference: Anna Goodman, Roger L. Mackett, James Paskins; Day length and weather effects on children's physical activity and participation in play, sports and active travel, Journal of Physical Activity and Health, 2011, x(x), pp.
Co-Authors Roger L. Mackett and James Paskins are based at the Centre for Transport Studies, University College London, London UK.
This report is independent research arising from a Post Doctoral Research Fellowship awarded to Anna Goodman by the National Institute for Health Research and based on two EPSRC funded studies: "Reducing children's car use: the health and potential car dependency impacts" (grant GR/N33638) and "Children's activities perceptions and behaviour in the local environment" (grant GR/T09378/01).
The views expressed in this publication are those of the author(s) and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health.
About the NIHR. The National Institute for Health Research provides the framework through which the research staff and research infrastructure of the NHS in England is positioned, maintained and managed as a national research facility. The NIHR provides the NHS with the support and infrastructure it needs to conduct first-class research funded by the Government and its partners alongside high quality patient care, education and training. Its aim is to support outstanding individuals (both leaders and collaborators), working in world-class facilities (both NHS and university), conducting leading edge research focused on the needs of patients. http://www.nihr.ac.uk
British Summer Time (BST) runs between the last Sunday in March and the last Sunday in October. The last change was made on Sunday 30 October 2011 at 2am. In March the UK clocks move forward by 1 hour and in October they move backwards by 1 hour. Since 1996 all member states of the European Union change their clocks on the same date at 1am Greenwich Mean Time.
About UCL. Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender, and the first to provide systematic teaching of law, architecture and medicine. UCL is among the world's top universities, as reflected by performance in a range of international rankings and tables. Alumni include Marie Stopes, Jonathan Dimbleby, Lord Woolf, Alexander Graham Bell, and members of the band Coldplay. UCL currently has over 13,000 undergraduate and 9,000 postgraduate students. Its annual income is over £700 million.
Website: http://www.ucl.ac.uk
Daylight Savings Bill: The UK currently changes the clocks forward by one hour during summertime ('Single Summer Time'), but the past decade has seen several proposals to extend this by changing the clocks forward by one extra hour year round ('Single/Double Summer Time'). The most recent of these proposals is a Daylight Saving Bill which had its second reading in the House of Commons on 3 December 2010
Journal
Journal of Physical Activity and Health