Seven consecutive years of Sleeptracker-AI data — spanning millions of nights of sleep — show a consistent, marked disruption in sleep patterns each fall when clocks are set back. The pattern repeats without exception. Arizona, which does not observe Daylight Saving Time, shows no corresponding disruption in the fall data — a built-in control that makes the causal relationship unambiguous.

The evidence is clear: eliminating the twice-yearly time change would preserve healthy sleep cycles and, in the modern context, restore a meaningful hour of post-work daylight that benefits both physical activity and wellbeing.