Don’t Spend the Hour

Not the Bad One

Two clock changes a year get treated the same way in most of what gets written about them. They are not the same.

A systematic review published this year in the European Journal of Epidemiology went through 157 studies from 36 countries and separated the two. The spring change was associated with more heart attacks and more fatal traffic accidents. The autumn change was associated with neither, and the review found no clear effect on psychiatric outcomes either.

What it did find for autumn was a possible increase in sleep duration, which it held at low confidence, and possible reductions in deaths and in workplace accidents, both at medium confidence. Its one high-confidence finding for the autumn change was an increase in crimes involving physical harm. The authors conclude that the effects are neither uniformly harmful nor uniformly beneficial.

Part of why the two get treated alike is that the complaint sounds the same both times. Something has been done to the day and nobody asked. In spring that complaint has physiology behind it. In autumn it is mostly about the evening going dark on the drive home, which is a real thing to dislike and a different kind of problem.

Which makes it the one worth using rather than surviving.

What Actually Moves

The hour is a single night. What lasts is the light.

After November 1 the sun comes up earlier by the clock and goes down earlier by the clock. Mornings get brighter sooner, which generally helps with waking. Evenings go dark sooner, which is the part people notice and dislike.

Light is what the body uses to set its internal timing. NIOSH’s own explanation of the mechanism is that light exposure at different times of day shifts that clock, which is why a change in when light arrives has any effect at all. The wall clock is not doing the work.

The evening is where people register it. Leaving work in the dark feels like a larger change than it is on paper, partly because it arrives all at once instead of creeping in the way the season has been doing for weeks already. The morning side of the trade goes mostly unnoticed, because fewer people are outside at that hour to notice it.

Where the Hour Goes

Here is the part that decides whether anything is gained.

Keep the usual bedtime on Saturday and the usual wake time on Sunday, and the hour turns into sleep. Stay up an hour later to use it and then rise at the same clock time, and nothing has been gained. Worse, that person has shifted themselves an hour later going into a season where the evenings are already dark.

The weekend after is usually where it comes undone. Two late nights put a person back where they started, with the week ahead to climb out of again.

The extra hour is the only one of its kind in the year. It is the single morning where sleeping the same amount leaves a person ahead rather than behind.

A Week, Not a Night

NIOSH puts adaptation at about a week, and the advice that follows from that is unglamorous. Keep a steady time for sleeping and waking. Get outside in the morning where possible, because that is the signal the body is reading.

A fixed wake time does more work than it looks like it should. It is the part of a sleep schedule a person actually controls, since nobody decides the moment they fall asleep. Holding the morning end steady pulls the rest back into line over several days, which is roughly the week NIOSH describes.

For anyone working rotating shifts or duty hours, the clock change lands on top of a schedule that is already fighting the body clock. The wake time anchor matters more there, not less, and it is harder to hold.

If It Was Already Broken

None of this addresses sleep that was a problem before the clock moved.

Sleep ranked in the top five concerns for every cohort in the member survey, and in the top three for Veterans and for family and caregivers. For a lot of people the November change will be a small thing landing on something much larger.

The clock change is worth using precisely because it is small. It asks for one decision on one night, and what it protects is an hour of sleep that most people hand back without noticing. That is a low bar, and it is still more than most years offer.

VA runs a sleep check-up that takes about five minutes and screens for sleep disorders, alongside a self-guided course built on cognitive behavioural therapy for insomnia. It is free, needs no registration, and is open to family and loved ones as well as Veterans. The person losing sleep in a household is often not the one with the service record.