Daylight Saving in GB; Is there evidence in favour of clock time on GMT?

  • Published: Centre for Technology Management, Department of Engineering and Judge Business School, University of Cambridge, 2007
  • Authors: B. Cronin and E. Garnsey
  • Date Added: 18 Mar 2013
  • Last Update: 18 Mar 2013
  • Format: pdf


Review of evidence neglected by policy makers.Examine the evidence on the impact of returning to GMT in winter

(1) on RTIs

(2) the alignment of activity patterns with solar time

3) on energy use patterns

(4) on generation costs and

(5) other issues relating to clock time policy are examined.


Re-analysis of existing data.

Key Findings:

  • No evidence in favour of imposing GMT in winter was found.

  • There would be a favourable impact from a policy change to GMT+1 in winter on all dimensions shown, with the exception of the impact on early morning workers. However working hours could be altered for particular groups, as in Scandinavia.

  • There is an early morning peak in RTIs from 8am to 9am, but a higher and longer lasting RTI peak occurs from 3pm to 6pm when activity rates are higher than in the morning.

  • In Scotland, as in the rest of GB, earlier timing of sunrise and sunset under GMT shifts light to the morning, when traffic is lighter, at the cost of an hour’s less light in the evening period when the traffic peak is heavier and longer than during the morning peak.

  • Clock time on GMT results in over a hundred unnecessary deaths on the road annually in GB, and over 40 deaths and serious injuries in Scotland. These tragedies entail massive costs for the NHS.

  • The available evidence is already more than sufficient to justify this policy change.

  • However the impact of setting the clocks back to Greenwich Mean Time after the end of British Summer Time is an institutional practice so well entrenched that it appears to be exempt from evidence-based policy making.

  • Whether a move to double summer time (GMT +2) would be beneficial is a separate question for which less evidence is available since this time regime is not currently applied.

  • The timing of sunrise and sunset is relevant to RTIs because clock time has a greater effect on the pattern of activity on the roads than does the incidence of daylight; for example most people return from work between 5pm and 6pm., whatever the timing of sunset. Reduced daylight reduces visibility and so provides less opportunity for drivers to react.

  • The extensive evidence that RTIs overall would be reduced by GMT+1 in winter has been overlooked.

  • Scottish MPs have not been provided with comprehensive and clearly explained evidence. The reduction in road RTIs from changing to GMT+1 all year would be no less in Scotland than the UK as a whole.


Scotland, NHS cost, Casualties, Evidence, GMT +2.


Outlines the main advantages of keeping clock on GMT+1 all year round. The research seems to be biased and is not peer reviewed.