On October 27, some countries will turn their clocks back an hour to mark the end of daylight saving time, a twice-a-year custom in 70 countries. Getty Images
On October 27, some countries will turn their clocks back an hour to mark the end of daylight saving time, a twice-a-year custom in 70 countries. Getty Images

It takes three days to 'get back to normal' after a holiday, research reveals