Changing the clocks back and forth twice per year has come under fire for its potential negative health impacts – but would moving to a permanent daylight saving time be good for our health?
The Canadian province of British Columbia this week made the move, which has cut the need to change the clocks twice per year altogether.
According to the province's premier, David Eby, this was done to improve people’s overall health, reduce disruptions for families, and stop the “significant amount of chaos” the clock changes have on “already busy lives”.
Research has shown in the days immediately after changing the clocks – which has a history of its own in New Zealand – there can be a negative impact on our physical and mental health, and even cause an increase in car accidents.
However, recent research from Canada shows they may not be better off by adopting a permanent daylight saving time.
The importance of morning light
In a recent article for The Conversation, Canadian professors Elizabeth Keys and Wendy Hall found the change to permanent daylight saving time could result in a "chronic mismatch" between people's biological clock and their daily schedules.
They said the body's internal clock, called the circadian rhythm, uses morning light to "reset", and regulate hormones, digestion, mood, along with other body functions.
In New Zealand, daylight saving starts at 2am on the last Sunday of September and ends at 3am on the first Sunday of April, giving us 27 weeks of daylight saving annually. The aim is to make better use of daylight in the evenings.
However, Auckland University professor Guy Warman said if New Zealand adopted a permanent daylight saving time, "it would be certainly worse for our circadian health" during the winter months.
"I think the key is that if we were in summertime the whole of the year, then we wouldn't be getting light in the morning, where it is really important to adjust our circadian clocks on a daily basis."
Warman acknowledged there is "certainly some evidence" which showed there are some negative impacts when changing the clocks, however "over the course of the whole year, it may be different".
"I think there are some data to suggest that changes to summertime and wintertime have short term effects that are negative," he said. "But there are also some studies that are showing that the changes to summertime and wintertime can have positive effects on our behaviour and health."
Following the research, Warman said he didn't believe it was "quite the dreadful thing" some believe.
"I think there needs to be further studies done on not just the negative, but the positive effects of changing from summertime to wintertime, and to make a balanced decision therein."
Instead, Warman suggested the debate should focus on other lifestyle factors which are proven to be harmful, such as reducing excessive shift work, or repeated timezone shifts.
A worse impact down south
British Columbia and New Zealand have different daylight patterns between the seasons due to their relative distances from the equator. While Vancouver has about 16 hours of daylight in summer, Auckland has 14.5 hours. But in winter, Vancouver has just 8 hours of daylight while Auckland has 9.5 hours.
The impact within New Zealand would also vary from north to south.
Southland MP Joseph Mooney suggested moving to permanent daylight saving time would not have a lot of support in his electorate, which would be affected the most by the change.
"Making daylight savings permanent would push Southland's darkest winter month sunrise to around 9.30am. That compares to 8.30am in Northland," he said.
"In Southland kids would be heading to school before sunrise. A lot of workers — especially in farming, trades, and other early‑start jobs — would be starting their day an hour deeper into the dark. And for many families, the whole morning routine would happen with no daylight at all."
Daylight saving in NZ ends on Sunday, April 5 at 3am, when clocks will be turned back one hour to 2am.
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