More daylight, better health: why we shouldn’t be putting the clocks back this weekendBMJ 2010; 341 doi: http://dx.doi.org/10.1136/bmj.c5964 (Published 27 October 2010) Cite this as: BMJ 2010;341:c5964
- Mayer Hillman, senior fellow emeritus, Policy Studies Institute, University of Westminster, London
Lack of exercise is a major public health problem in the United Kingdom, contributing to the incidence of chronic illness. Adults are recommended to engage in at least 30 minutes of moderate or vigorous activity daily and children at least an hour. However, surveys have shown a trend towards declining fitness, on the basis of which it has been predicted that more than half the population will be clinically obese by 2050.
Health experts have proposed urgent action to remedy this situation, and the government now aims to get far more of the inactive population walking or gardening regularly or, preferably, taking up more vigorous physical activity, such as sports, aerobics, or cycling (especially as a means of travel). Although most people are aware of the benefits—a lessened risk of coronary heart disease, obesity, diabetes, hypertension, and some cancers—routine physical activity features in few people’s everyday lives. Only a small proportion of adults are motivated to undertake it throughout the year, and the school curriculum allocates insufficient time for it. In addition to removing the social, economic, and psychological barriers to activity, the measure seen to be most effective is providing more public facilities and open spaces—and networks of safe walking and cycling routes to reach them—that are sufficiently local that the journeys to get to them are not so long that the actual activity is curtailed.
Research has shown that people are happier, more energetic, and less likely to be sick in the longer and brighter days of summer, whereas their mood tends to decline—and anxious and depressive states to intensify—during the shorter and duller days of winter. People have a greater sense of wellbeing in daylight and overwhelmingly prefer it to artificial light. The common reaction to the prospect of less daylight and sunlight when the clocks are put back at the end of October, signalling as it does the end of outdoor activity and the onset of a largely indoor leisure life, is a negative one.
The source of the problem is that on average over the year only one or two of our waking hours in the mornings are spent in darkness, whereas nearly half of the 10-11 waking hours after midday are in darkness. The critical limiting factor is obviously the onset of dusk.
In 1988 the Policy Studies Institute published a study on the consequences of the UK keeping British Summer Time during winter (by not putting the clocks back in October in one year) but still putting clocks forward in the subsequent spring, thus putting the UK one hour ahead of Greenwich Mean Time in the winter and two hours ahead in summer (known as “Single/Double Summer Time”).1 This study and a just published study of the specific effects of such a move on Scottish life point to a wide range of advantages.2 Not the least of these is the additional hour of evening daylight in every day of the year but, because we get up after sunrise for most of the year, the loss of an hour of morning daylight in winter only.
It is surprising therefore that the positive effect of increasing the number of “accessible” daylight hours in this way in terms of promoting physical health and wellbeing has been consistently overlooked. As most children are restricted from going out after dark, the lighter evenings would enable parents to let them spend more time outdoors. A significant majority of older people impose a curfew on themselves, preventing them from going out after dark, owing to anxiety about assault, and poorer vision and hearing. The extra hour of evening daylight would lessen these concerns and enable far wider take-up of outdoor leisure and social activities. The additional hours of daylight would considerably increase opportunities for outdoor leisure activities: about 300 more for adults and 200 more for children each year, given typical daily patterns of activity.
There is strong support for such a clock change among all road safety organisations; many sectors of industry, especially tourism and leisure services; nearly all bodies involved in sport, recreational, and cultural activities and those engaged in overseas trade, travel, and communications; and groups representing children, teenagers, women, pensioners, and people living in rural communities. Any government introducing this reform is therefore likely to reap substantial political rewards, as public opinion in the UK has repeatedly been shown to favour the change. The ratio of those in favour to those against is now about 4:1 in England and Wales, while in Scotland opinion is fairly evenly divided despite being coloured by the unbalanced portrayal of the effects of a change in sections of the Scottish media.
Adopting this proposal for a clock change is an effective, practical, and remarkably easily managed way to better align our waking hours with the available daylight during the year. It must be rare to find a means of vastly improving the health and wellbeing of nearly everyone in the population; here we have it, and it only requires a majority of MPs walking through the “ayes” lobby in the House of Commons.
Cite this as: BMJ 2010;341:c5964