The idea of changing the clocks to take advantage of more daylight at either end of the working day has been kicking around for ages. But it wasn’t until the coal shortages of the First World War threatened to plunge homes and factories into darkness that governments took action. Germany led the way in 1916 and Britain quickly followed suit – advancing the clocks one hour from 21st May to 1st October. Originally known as Daylight Saving Time or DST (which doesn’t really make sense because it doesn’t actually save any daylight), the term was soon replaced by British Summer Time or BST (which does make sense).
On the earth’s equator, day length is always 12 hours, while at the north and south poles it can vary from zero to 24 hours depending on the time of year. And this is why different countries take different approaches to Daylight Saving Time. Broadly speaking, countries in the tropical belt don’t bother changing their clocks, unlike many other countries with large seasonal daylight ranges. Most of Europe and North America use DST. China and Russia used to observe DST but don’t anymore. While in the antipodes, New Zealand does observe DST, while most of Australia doesn’t, apart from the highly populated southeastern region, which does.
Of course, moving the clocks forward one hour doesn’t actually create any extra daylight, but it does add an extra hour of light to our evening schedules – which is great for anyone who likes to get out and about or play sport after a day at work. By aligning our active hours more closely with natural daylight hours, we also become less reliant on artificial energy-consuming light. And it’s been argued that DST improves road safety because it means more journeys take place in daylight. In fact, the Royal Society for the Prevention of Accidents has campaigned for the adoption of daylight saving all year round in order to avoid the sudden darkness of autumn.
Not surprisingly, the advantages of DST are offset by some disadvantages, which probably explains why the debate around the issue has ground on for years. The most obvious downside of adopting DST is the impact on our health. Suddenly switching an hour forwards or backwards can disrupt our circadian rhythm – the body’s natural 24-hour sleep-wake cycle, and this can have a variety of effects on our wellbeing. Studies have shown an increase in the number of strokes after the switch to DST, with a similar spike in heart attacks in the first three weekdays following the clocks going forward. And the disruptions in sleep patterns can also affect energy levels and even your immune system.