What Is the Deal With Daylight Saving Time?

Why do we really practice this age-old change?
Published October 28, 2022

Twice a year, about 40% of the countries around the world adjust their clocks back and forth. In March we set the clocks forward an hour, entering a period known as daylight saving time (DST). In November this period ends, and we move the clocks back. This seasonal practice has been known to cause issues ranging from poor sleep to missed flights and more car accidents.


So what is the deal with daylight saving time? Often wrongly referred to as “Daylight Savings,” with an “s” at the end, the official adoption of this change goes back to WWI. In 1915 the German Government was looking for ways to conserve energy resources while they were scarce during the war. Their solution was to put the clocks forward one hour in the spring to allow for more light during work hours. After Germany implemented this practice so too did nearly every other country that fought in the war, including Canada, the United States, and much of Europe. Following the war, Canada dropped the change only to pick it back up for WWII. Since then, there have been many adjustments made to the practice in Canada and the USA but remains in place for most provinces, territories and states.

Help or hazard?

While this practice certainly seems to have been beneficial as a means to conserve energy, many people question its use today.

The “spring forward” in March appears to cause the most trouble.The loss of one hour of sleep negatively impacts our circadian rhythm, which is set by the timing and amount of bright light exposure we get in a day. When the time changes, our internal clocks are out of sync with the sun leaving us feeling tired in the morning and awake at night. In general, DST is known to cause short-term health troubles like sleep issues, fatigue, and blood pressure changes.

There are even more severe changes that have been reported in the week following DST. For example, one US study found that on the Monday following DST in March there was a 24% higher risk of heart attacks. This same study found that during the “fall back” in November this risk decreased by 21%. The loss of sleep appears to exacerbate people’s underlying heart and health issues, increasing their risk of heart attacks. Similarly, there has been found to have a 6% increase in fatal car accidents in the week following the “spring forward.” This seems to be caused by an entire population experiencing sleep disruptions at the same time.

How to adjust

Whether it is time to move the clocks forward or back there are some tips to help make the transition easier on your body and schedule.

  • Keep your sleep schedule: it might be tempting to go to bed earlier or later, but it’s better to try to adjust to the new timing and light.
  • Don’t nap: this can make it harder to sleep at night.
  • Go to bed at your normal time the night of the change: In the fall, take advantage of the extra hour.
  • Don’t alter your caffeine routine: Even though you might be more tired than usual, try to keep your caffeine intake the same.
  • Prioritize light exposure: light exposure is the main driver for our circadian rhythm. Getting light exposure in the week following the time changes can help your internal clock adjust to the new time.
  • Exercise in the morning: Dark mornings in the fall and winter can be tough. Getting up and moving will help you wake up and warm up.