When the clocks go back, it means that the time is set back by one hour, usually in the fall or autumn season. This means that people get an extra hour of sleep, and the mornings are lighter as a result. The main reason for turning the clocks back was to make the most of the daylight available in the summer. The idea is to make better use of the daylight and conserve energy. The clocks go back on the last Sunday of October at 2:00 am in the UK. The transition to and from Daylight Saving Time has been reported to cause jet-lag-type symptoms, an increased risk of adverse cardiovascular events, mood disorders, and vehicle collisions.