Permanent Daylight Saving could create new problems, study shows

The debate over whether moving the clock back in the fall and then forward in the spring for daylight saving time (DST) is unnecessary has led several states to consider voting it out of practice. But now, the results of a new study suggest that permanent DST would make winter mornings more of a challenge, while undermining efforts to help teenagers achieve more adequate amounts of sleep before school start times.

“There has been a long-term, very active debate in the USA and other countries on the difficulties teenagers have in getting up for school,” said study co-author Anne Skeldon, who is a Mathematics professor at the University of Surrey. “Similar discussions on school start times and on permanent daylight saving/standard time are happening in Europe. It seemed important to us to point out that moving to permanent daylight saving will undermine any benefits on sleep timing of shifting school start time later.”

Currently, one bill is making its way through the California state legislature which would prohibit middle and high schools from starting earlier than 8:30, while another bill is being considered to transition to permanent DST.

Professor Skeldon explained that thinking through why permanent DST would negate changes in school start times is a bit tricky. This is because it requires understanding how environmental time, internal biological time, and the time we set on our clocks are related to each other and how they shift over the course of the year.

Permanent DST would mean that sunrise would come at an even later clock time than it already does during those shorter days of the winter. The study authors said that, as a result, waking at 7 a.m. during DST leads to the same degree of misalignment as waking at 6 a.m. during Standard Time. “With permanent DST, schools would need to delay start times by one hour during the winter months just to maintain the status quo!”

The researchers also acknowledged the possibility that people living indoors under electrical lighting are not affected very much by shifts in sunrise. However, if this is the case, school start times do not really matter in the first place.

“If we are not entrained to solar time, switching to DST will have no impact on adolescent sleep, but Bill SB-328 delaying school start times is pointless,” wrote the study authors. “If we are completely or partially entrained to solar time, Bill AB-807 leading to permanent DST is bad for adolescent sleep (and the sleep of others) and negates the effect of later school start times.”

To solve this debate, they said, more research is needed to understand how light exposure affects the biological clocks and sleep quality of people living in different environments.

“We know that spending most of our lives inside and having the lights on late into the evening has had profound effects on when we sleep, but we still have much to learn about exactly how much this matters,” said Professor Skeldon.

The study is published in the journal Current Biology.

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By Chrissy Sexton, Earth.com Staff Writer