Does daylight saving affect our health?

There’s nothing like turning back the clock at the end of daylight saving time to remind yourself that time is an illusion and nothing’s real.

But there’s more to the science of daylight saving than scoring an extra hour of sleep this weekend.

History of chasing daylight

Benjamin Franklin first advocated for something like daylight saving time (DST) in 1784, when he was shocked to discover he’d been sleeping through hours of daylight in the morning. Franklin’s suggested solution was to wake everyone up with a cannon firing at sunrise.

It wasn’t until the first world war that time-shifting schemes were put into place around the world, starting with Germany.

DST helped save money on fuel during the war as sunlight replaced artificial light, but was generally unpopular and dropped in most places soon after. It’s remained controversial ever since.

Australia and DST

In Australia, DST has a long and chequered history. Queensland had a particularly hard time with the concept, dropping it in 1972, reintroducing it in 1989 and then abandoning it again after a referendum in 1992.

Western Australia also adopted and abandoned DST twice before trialling and rejecting it again in 2009. This leaves us with DST in all Australian states and territories except for Queensland, WA, and the Northern Territory (where it was never reintroduced after WW2).

What are the negative effects?

Daylight saving – especially the transition at the start, where we “spring forward” and lose an hour of sleep – has been associated with all kinds of negative health impacts.

Studies have shown the lost hour can affect our functioning for up to a week.

More traffic accidents and workplace injuries have been reported in the week following the change, and some studies find an increase in heart attacks.

The switch has also been linked to a dramatic increase in cyberloafing (ie wasting time on the internet when you should be working – possibly what you’re doing right now), and unsurprisingly, can lead to people missing their appointments

DST is like jet lag

Associate Professor Jill Dorrian, from the University of South Australia, says daylight saving works the same as travelling across time zones. By adjusting the time, we change our circadian rhythms, “creating a very mild jet lag,” she says.

“Our circadian rhythm is designed for us to have the same habits each day,” Dorrian explains. All our bodily processes follow a 24-hour rhythm, controlled by “the master clock in the brain, that gets light through the eye – that light tells the brain whether it’s day or night, and also helps keep all our other physiological functions in that rhythm.”

When we have a regular sleep schedule and get enough sleep, “all our rhythms are in sync and everything is great,” Dorrian says.

But DST can mess all that up in one short hour. “For most people, it takes a few days to a week to shift your rhythm,” Dorrian says.

Do we lose or gain sleep?

Some studies show that when we “fall back,” gaining an hour of sleep, these negative effects are reversed – with fewer heart attacks and accidents observed in the week to follow. But it might not be time to strategically book your acrobatic pilot’s test just yet: evidence suggests we wind up losing sleep at both ends.

While most people look forward to the extra snooze time, “a lot of people actually don’t get that extra hour of sleep,” Dorrian says.

“They’re waking up earlier than they should, and they’re awake for longer during the day, and they’re losing a little bit of sleep each night. This transition we’re about to go through can also have a negative impact.”

Are there positive effects?

The negative aspects of DST are enough to lead some researchers to propose an end to the practice altogether.

But Dr David Prerau, DST expert and author of Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time, says the health benefits of daylight saving “significantly outweigh its negative effects on health”.

Prerau says that while DST might have short-term drawbacks when we change the clocks, “the health benefits of DST last over the entire DST period”.

Studies have shown an increase in activity during DST, as the daylight “gets people outdoors in the evening, getting more exercise, rather than being sedentary indoors,” Prerau says.

“TV ratings go down while gardening activities, park attendance and sports participation all go up.” According to Prerau, daylight saving helps people feel safer at night, and reduces crime and traffic fatalities.

Can you make the transition easier?

There are ways to help ease the transition to and from DST. Jill Dorrian suggests getting morning light at the same time each day, keeping your new sleep schedule consistent, and trying to get enough sleep leading up to the transition.

“If you’re already tired, and then you put this stress on the system on top of it, then you might be in more trouble,” she says.  

She adds that the switch is tougher for some people, such as dedicated morning larks or night owls, and those with psychiatric illnesses like bipolar disorder or depression. “Regular sleep schedules are very helpful in managing some of these illnesses,” Dorrian says.

You might want to put an end to it or you might want to double it, but it’s here now. So tuck yourself in and sleep tight – the sun will still rise tomorrow (but who knows at what time).