Quick Answer: A clock change is a one-hour jet lag that everyone in your time zone gets at once. The spring change, when you lose an hour, is harder, because your body clock finds it easier to run later than earlier. Shifting your sleep 15 to 20 minutes a night for a few nights beforehand, and getting morning light afterwards, makes either change much easier. The free daylight saving time planner builds a night-by-night plan for your region.
The Next Clock Changes#
- New Zealand: clocks go forward on Sunday 27 September 2026.
- Australia (NSW, Victoria, ACT, Tasmania, South Australia): forward on Sunday 4 October 2026.
- UK and Europe: back on Sunday 25 October 2026.
- US and Canada: back on Sunday 1 November 2026.
Why Your Body Doesn't Change With the Clock#
Your body clock keeps its own time, set mainly by when you see light. It can shift, but only by about an hour a day at most, and often less. So after a clock change you spend a few days with your body still running on the old time: sleepy at the wrong moments, awake when you'd rather sleep.
Why Spring Forward Is Harder#
In spring you lose an hour, so your body has to shift earlier to keep up, and for most people that's the harder direction. Left without time cues, the human body clock runs slightly longer than 24 hours, about 24.2 on average (Czeisler et al., 1999, Science), so drifting later comes naturally and moving earlier takes effort. Night owls usually feel it most.
The spring change also comes with a short-term cost. Studies have linked the days after it to a small rise in heart attacks (Janszky and Ljung, 2008, New England Journal of Medicine) and in fatal car crashes (Fritz et al., 2020, Current Biology). The increases are small, and they're associations, but they're part of why the American Academy of Sleep Medicine called in a 2020 position statement for ending seasonal clock changes in favour of permanent standard time.
The Autumn Change#
When the clocks go back you gain an hour, which is gentler. Many people wake an hour early for a few days, feel sleepy early in the evening, and notice how suddenly dark the afternoons are. If you tend toward low mood in winter, the loss of evening light can be noticeable; the winter light guide covers what helps.
How to Prepare#
- 1.Shift gradually. For three or four nights before the change, move your bedtime and wake time 15 to 20 minutes a night: earlier before a spring change, later before an autumn one. This is the approach the American Academy of Sleep Medicine recommends.
- 2.Use light on purpose. Around a spring change, get about 20 minutes of outdoor light soon after waking and keep evenings dim. Before an autumn change, get light in the late afternoon and keep early mornings dim. Never look directly at the sun.
- 3.Protect the first few nights. Keep caffeine well clear of bedtime; for one average cup that's roughly five hours for an average metaboliser. The caffeine cutoff calculator finds yours.
- 4.Keep your wake time steady afterwards, including the first weekend.
Children often take longest to adjust. Move their bedtime in 10 to 15 minute steps over the week before the change.
Where ARC Fits#
ARC works out clock changes from your time zone, with nothing to set up. It warns you the evening before, stays with you through the Sunday and Monday people actually feel, and keeps quiet in time zones that don't change. The rest of the day follows: a 20-minute morning light timer from your real sunrise and a last safe coffee solved from your own bedtime.