Canadians are sleep-deprived. Research from Statistics Canada suggests we're getting about one hour less sleep each night than a decade ago, and fully one-third of us are not getting the minimum amount of sleep our bodies require.
With this in mind, there will probably be a great deal of rejoicing across much of the country on Nov. 3. Canadians who observe daylight savings time turn back their clocks and gain an extra hour of sleep on Sunday morning. Of course, there will also be grumbling in the spring when that hour is clawed back.
Changing our clocks twice a year can have an impact on our lives in another way, however. Research suggests that daylight savings time affects road safety. In this blog, I'll explain why the biannual time change causes a short-term rise in car accidents and pedestrian fatalities, but likely prevents more injuries and deaths on the roads over the long-term.
The Body Clock
Although we like to say that we gain or lose an hour of sleep during daylight savings time changes, researchers have found that we lose about 40 minutes of sleep on average when clocks "spring forward". We gain about 12 minutes of additional sleep when we "fall back." Nevertheless, the effect on our body is greater than what these numbers might suggest.
Our internal clocks, which control our circadian rhythm, get thrown for a loop when our usual bedtimes and wake-up times change. If our circadian rhythms are disrupted, we experience effects on hormone levels that control sleep, metabolism and mood; these changes can lead to secondary effects.
The incidence of heart attacks and strokes – particularly for people already at risk – increases in the period immediately following a time change. Research also indicates that there is a 20 per cent drop in productivity on the first workday following a time change, as our minds are less alert and focused. The effects are far greater in the springtime, when workplace accidents spike immediately following the time change. But there are noticeable increases in another kind of accident following the autumn change.
More Dangerous Roads?
Immediately following daylight savings time changes at either point in year, there is a short-term spike in the number of vehicular accidents.
A 2014 University of Colorado study cited short-term sleep deprivation as the reason for a 17 per cent increase in traffic accident-related deaths on the Monday following the "spring forward" time change. University of British Columbia sleep researchers also found a five to seven per cent increase in accident fatalities over the three-day period following the change. Within a week of springing forward, accident rates return to normal.
The same pattern doesn't occur when we "fall back". However, studies have noted fatal pedestrian deaths are three times more likely to occur during the morning commute in the three weeks after this time change. Lower light levels, rather than sleep deprivation, cause these morning accidents as there is no similar increase at other times of the day. Drivers and pedestrians were found not to adapt their behaviour to accommodate the sudden change in visibility.
Despite these short-term negative effects, over the long-term some experts contend that daylight savings time has a net safety benefit because more accidents and injuries occur during periods of low light. Maximizing daylight during regular work hours helps more than it hurts.
What Can You Do?
Short of moving to Saskatchewan, or one of the handful of communities in the country that do not observe daylight savings time, everyone will have to muddle through this disruption to our sleep cycle twice a year.
You can help your body accommodate the change by gradually shifting your bedtime and wake-up time by 15-20 minutes in the week leading up to the change. A healthy diet, good hydration, and increased exposure to sunlight (Vitamin D) and physical activity during the day will also help your body cope.
Finally, be extra vigilant when on the road. Avoid driving when you're drowsy or tired. Be aware that even though you may feel fine, the time change can cause other drivers to be more tired and less focused than usual. Also, when walking during times with low light, be sure to wear reflective material on your clothes or carry a light to improve your visibility.
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