Early on Sunday morning, clocks across the UK will be rolled back an hour, marking the end of the summer’s Daylight Saving Time (DST). You can check your local clock change time and date here.
So should we be despairing at the darker winter mornings, or revelling in the extra hour in bed?
Why do we change the clocks?
The idea was first proposed in Britain in 1907 by a keen horse-rider, William Willett, who was incensed at the waste of useful daylight on summer mornings. The government finally introduced a Daylight Saving Time scheme in 1916, a few weeks after Germany. It was felt that any system that could save fuel and money during the First World War was worth a try.
What does it mean for our sleep?
The clock change means an abrupt shift in the external cues which help our internal body clock to maintain a 24-hour circadian rhythm track. These external time cues are called ‘zeitgebers’, and include light, temperature, exercise and food/drink intake.
It can take several days for our internal biological clock to re-synchronise with a new schedule, whether it’s a clock change or a timezone difference. For some people, this desynchrony leads to disrupted sleep, and feeling tired during the day.
A misalignment between external cues and our internal body clock can also have more serious consequences. For example, there is a spike in the risk of heart attacks spikes on Monday mornings. This is thought to be due to a combination of the stress of a new working week and sudden changes in our sleep-wake cycle. By studying the rates of heart attacks over four years, US researchers showed a 25% increase on the Monday following the shift to DST in Spring when clocks were rolled forwards, reducing our sleep. Conversely – and positively for next week – there was a 21% decrease in heart attacks when the clocks were rolled back in the Autumn.
How can we re-establish our sleep-wake cycles following the clock change?
- Get up at the same time in the morning each day – which means enjoying an extra hour in bed this weekend. It may still take take a few days to adjust to the new schedule, but routine is key for creating a consistent drive to sleep each evening.
- In the winter, with fewer hours of daylight overall, it’s important to seek out exposure to morning light where you can. Light is a strong cue to alert the internal clock, and daylight ensures it remains synchronised to the 24-hour day. Lack of light exposure during the day can result in a drift of the internal body clock, making it harder to get up in the morning in the winter.
- Avoid bright lights for at least an hour before bed. Bright light inhibits the production of melatonin (a hormone involved in the timing and regulation of sleep) which can leave us feeling more alert. Minimise your use of electronic gadgets for at least an hour before you go to bed to give yourself time to wind down.