Analysis Backs Permanent Standard Time Over Permanent Daylight Saving

The lead author, Professor Raymond Lam of the University of British Columbia, said ending the clock change solves one problem but creates another decision: which time to live on year-round. "The health evidence points to standard time, largely because morning light matters for our body clocks, sleep, and mood," Lam said, according to Sci.News.

Lam and colleagues examined the health consequences of permanent standard time, which keeps clocks more closely aligned with human circadian biology, and permanent daylight saving time. They concluded that the accumulated evidence favors permanent standard time. The distinction becomes especially important in winter.

Permanent daylight saving would push sunrise an hour later. In Toronto, the latest winter sunrise would be at 8:51 a.m., compared with 7:51 a.m. under permanent standard time. In Calgary, those times would be 9:40 a.m. and 8:40 a.m., respectively.

The extra hour of morning darkness could mean people travel to work or school before sunrise, while more daylight would be shifted to the evening. The change could affect sleep, mood, learning and productivity, particularly among people who already have difficulty sleeping or must follow early schedules.

The study says the issue is rooted in the body's internal clock. "Our biological clocks need morning light to stay synchronized with the 24-hour day," said Simon Fraser University Professor Ralph Mistlberger, a co-author. "Permanent daylight saving time moves that light an hour later just when winter mornings are already darkest."

The analysis also highlights concerns about seasonal depression. By delaying natural morning light, permanent daylight saving time would act in the opposite direction, potentially weakening an important circadian signal, the authors say.

The findings arrive as permanent daylight saving time has emerged as the preferred option in most states and provinces considering an end to the twice-yearly clock change, according to the Slashdot post that shared the analysis.