Clocks change mainly to make better use of daylight and save energy, though the practice is debated for health and practical reasons.
What daylight saving time (DST) aims to do
- Move clocks forward in spring to shift one hour of daylight from the morning to the evening.
- Move clocks back in autumn to return to standard time, giving more morning daylight in winter.
- The motivation has historically included energy savings, aligning waking hours with daylight, and supporting activities after work or school.
Why this causes a time shift
- The change is biannual: typically forward one hour in spring and backward one hour in autumn.
- In practice, this alters circadian rhythms and daily routines, which can affect sleep, mood, and accident risk around the transitions.
Current status and regional variations
- Not all places observe DST year-round; some regions do not use DST at all (e.g., certain U.S. states and territories, and some European countries during specific periods). Local rules vary by country and region.
Common questions
- Do I need to adjust devices automatically? Many smartphones and connected devices update automatically, but clocks not connected to the internet may require manual adjustment.
- Health and safety: transitions, especially the spring shift, have been linked to sleep disruption, brief increases in heart-related events, and traffic incidents in some studies, though effects vary by individual. The autumn shift generally causes less disruption.
If you’d like, specify your country or region and I can tailor the explanation to your local DST rules and key dates for the current year.
