The hour you lost this morning, and where it comes from

At 2 a.m. this morning, most of the United States moved its clocks forward an hour. Nobody slept it. The hour was taken from the night, by statute, from roughly 330 million people at once, and tomorrow morning is the one day a year the entire country wakes up jet-lagged in the same direction. It is also the best natural experiment we have on what one hour of lost sleep does, because the sleep scientists have been watching it for decades.

What the evidence says. The American Academy of Sleep Medicine's position, first issued in 2020 and restated in 2023, is that the United States should drop the clock changes and keep permanent standard time, which lines up best with the body's clock. Its statement cites higher rates of motor-vehicle accidents, cardiovascular events and mood disturbances in the days after the spring change, and a 2019 survey in which 55% of adults said they felt tired afterward. The spring change is the harmful one; the fall change is the gentle one. The pattern is the lesson: the body tolerates a schedule, not a shift.

Loree’s take

The week after the spring change, my waiting room is a study in margin. The patients who sleep seven and a half hours barely notice. The patients who sleep six notice everything: the headache, the appetite, the short temper, the blood sugar. One hour did not do that. One hour removed the last of a buffer that was already gone. If tomorrow is hard, it is telling you about every other Monday.

Ben’s take

As an engineer I find it remarkable that we apply a one-hour phase shift to a nation's circadian clocks twice a year and call it a convenience. No system I ever built would tolerate that without a fault report. The fault reports exist; they are the accident and heart-attack statistics the AASM cites. We just don't file them under "the clock."

The practical version. The lost hour is not recovered by coffee; it is recovered by going to bed. The sleep literature's most consistent finding — short sleep associated with higher mortality, and with nearly every chronic disease that kills Americans — is about the nights, plural. One lost hour is a nudge. What you do with the next seven nights is the data.