The power of policy to influence behaviour change: daylight saving and its effect on physical activity

Objective:To measure the impact of the introduction of daylight saving in Western Australia in December 2006 on when during the day adults engaged in physical activity.Methods:In early December 2006, 1,300 Western Australian adults were telephoned and asked about how the introduction of daylight saving would influence when during the day they typically engaged in physical activity. At the end of the daylight saving period in March 2007, 1,083 of the baseline cohort agreed to answer questions relating to how daylight saving had affected when during the day they were physically active.Results:Almost half the cohort (45.5%) reported that daylight saving had affected when during the day they were physically active. During daylight saving fewer people exercised in the morning and more people exercised in the evening. When analysed at the individual level, 23% of the cohort ceased to exercise in the morning during daylight saving and 22% exercised in the evening only during daylight saving. In addition, to changes in when during the day people exercised, there was also an overall reduction in the average number of daily exercise sessions, with 8% not exercising at all during daylight saving.Conclusions:The results suggest that the introduction of daylight saving, a relatively modest compulsory change to increase daylight by one hour had an impact on patterns of when during the day people were physically active.Implications:The study results reinforce the value of focusing on policy as an effective means of supporting population behaviour change.