The Control Group That Lives in Arizona

A viral clip turns one Monday's heart attacks into a seasonal toll

November 2, 20262 minute read

Hand a podcast host a statistic with no denominator and the jaw hits the mic before anyone asks "per what?" In January, @VigilantFox shared a Joe Rogan clip in which sleep scientist Matthew Walker says that after we spring forward "we see a subsequent 24% INCREASE in heart attacks," and roughly 150,000 viewers watched Rogan's brain nearly explode, per the post, over a number with its fine print torn off.

Sandhu and colleagues produced the figure in a 2014 Open Heart study of heart attacks treated with angioplasty at Michigan hospitals. Their 24% jump showed up on a single Monday after the spring change. Weekly totals held steady, and the Tuesday after fall back saw 21% fewer cases. The authors concluded the clock shift moves the timing of heart attacks without changing how many happen, with patients reaching the cath lab a few days early like shoppers camped outside a Black Friday doorbuster.

Pooled data are less viral. A 2019 meta-analysis of seven studies covering more than 115,000 people found about 5% more heart attacks in the week after spring forward and no change after fall back. A 2025 US registry of nearly 169,000 patients found no significant difference in either season.

Crash research shows why a comparison group matters. A 2020 study reported 6% more fatal crashes in the week after spring forward than in nearby weeks, with no comparison against places that skip the switch. A 2026 study used Arizona and Hawaii, where clocks never move, as controls and found overall fatal crashes rose 0.2%, statistically nothing, though morning crashes still climbed.

Clocks fell back yesterday, so enjoy the bonus hour with your heart's blessing. The House, meanwhile, passed the Sunshine Protection Act this summer to make daylight time permanent, the opposite of what sleep medicine groups recommend.