The Health Risks of Permanent Daylight Saving Time

Permanent daylight saving time would keep clocks from changing twice each year, but it would also move one hour of morning daylight into the evening. Morning light is a powerful biological signal for anchoring the body clock, while evening light does not provide the same effect. Sleep scientists report that the spring clock change causes measurable spikes in car crashes, heart attacks, and workplace injuries due to acute sleep loss. The U.S. previously tried permanent daylight saving time in the 1970s and repealed it within a year after public backlash. Evidence-based recommendations favor permanent standard time, and permanent DST could worsen existing sleep deprivation and mental health challenges for teens.

"Permanent daylight saving time would keep clocks from changing twice each year, but it would also move one hour of morning daylight into the evening. Morning sunlight is among the most powerful biological signals we have for anchoring the body clock, while evening light does not provide the same biological benefit. That shift can disrupt circadian rhythms that regulate mood and sleep, undermining the very public health goal of reducing harm from clock changes."

"Each March, in the week following the clock change where we spring forward, we see a measurable spike in car crashes, heart attacks, and workplace injuries, all driven by the acute sleep loss of a single hour. Ending that biannual disruption is a legitimate public health goal. The disagreement lies in which permanent time to choose, because the choice determines whether morning light stays aligned with the body clock."

"Congress wants to lock in daylight saving time, and they frequently cite evidence that permanent daylight saving time is good for public health. But actually, the science supports the opposite: Permanent standard time. That distinction matters far more than most people realize, because the length of the day is set by Earth’s orbit, while daylight saving time only shifts when sunlight occurs relative to the clock."

"The U.S. tried permanent DST in the 1970s and repealed it within a year due to public backlash. Sleep scientists back permanent standard time, not DST, as the evidence-based fix. Permanent DST could exacerbate the existing mental health and sleep deprivation in teens, making the stakes higher than convenience alone."

Read at Psychology Today