Elizabeth Keys, Wendy Hall, The Conversation
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The British Columbia government recently announced the province will adopt permanent daylight saving time (DST). It framed the decision as a way to improve health, reduce disruptions, simplify scheduling and provide more evening daylight.
The adoption of permanent DST raises significant concerns about social jetlag and long-term health impacts. Scientific evidence indicates that permanent DST results in a chronic mismatch between people’s daily clock-based schedules and their internal biological clock.
This mismatch is known as social jetlag, results in sleep deprivation and negatively impacts health, as detailed by the Canadian Sleep Society, Canadian Society for Chronobiology, Canadian Sleep Research Consortium and the American Academy of Sleep Medicine.
As nurses conducting pediatric sleep research, our focus is on promoting adequate sleep for children, adolescents and their families. We are particularly concerned about the effect of permanent DST on adolescents’ sleep because they already experience social jetlag.
Circadian rhythm
Our internal body clock uses morning light to help us “reset” our circadian rhythm. Light helps regulate our internal body functions, such as digestion, metabolism, hormone regulation and mood. This daily light reset helps people synchronize their biological clocks with the sun.
Canada’s northern latitude gives Canadians a morning dose of daylight in the summer months. The switch back to standard time in the fall provides some morning daylight as the days shorten. That will not occur with permanent DST, which — unlike maintaining standard time all year round — maintains the artificial one-hour time switch of DST permanently.
DST changes the clock time without changing sun time, so circadian rhythms are not synchronized with school and work obligations, resulting in social jetlag. Social jetlag increases the risk of smoking, higher alcohol and caffeine consumption, and a higher incidence of mental health problems. It also increases risk for obesity, diabetes and cardiovascular problems.
One in three Canadian adolescents do not get the recommended eight to 10 hours of sleep per night. Recent estimates suggest more than half of teens do not get enough sleep.
Social jetlag is already common in adolescents, who experience a “perfect storm” for sleep deprivation. This perfect storm is caused by biological (such as hormonal) and psycho-social shifts towards later bedtimes and wake times. Social jetlag occurs because they have to get up for school on weekdays. Layering permanent DST on already existing social jetlag will likely worsen the perfect storm for adolescent sleep deprivation.
The severity of adolescent’s sleep deprivation and social jetlag is shown by the difference in the amount and timing of sleep they get on weekdays (when they have to get up for school or work) compared to weekends (when many people can sleep in). On average, Canadian adolescents sleep about one hour more on weekends than weekdays, with larger differences observed for female adolescents and those who identified beyond a gender binary.
Chronic sleep loss in adolescents is linked to problems with attention, behaviour and learning, and to increased risk of depression and self-harm. A recent review reported that adolescents’ shorter sleep duration was associated with a 55 per cent increase in the likelihood of mood deficits, such as anger, depression, negative affect and anxiety. Even younger adolescents (14 years) with less than seven hours of sleep had increased risk for drug use, anti-social behaviour and sensation-seeking.
Sleep duration is a relatively modifiable factor that can protect the mental health of adolescents. When Russia adopted permanent DST in 2011 (before switching back in 2014), adolescents experienced higher rates of sleep deprivation, increased social jetlag and increased depressed mood in the winter, especially for those located in more northern communities.
Late sunrises
Canada’s wider variations in day and night lengths will exacerbate effects of permanent DST. For example, adopting permanent DST means that sunrise in cities like Victoria, Vancouver and Kamloops won’t happen until after 9 a.m. in the middle of winter. This would apply to many other cities, including Calgary, Edmonton, Regina, Winnipeg and Saint John if permanent DST were adopted in those regions.
Late sunrises will especially impact more northern communities, like Fort Saint John where the sun won’t rise until after 10:30 a.m. in December. More northern communities, including many Indigenous, rural and remote communities, often already experience health inequities, including reduced access to medical services and other mental health resources. This reduced access may worsen the impact of permanent DST on sleep and mental health.
The experiment with permanent DST is likely to have significant effects over time. Evidence suggests negative effects on adolescents’ sleep and well-being. Researchers, health-care providers, policymakers and the public will need to work together to monitor the sleep duration, mood, health behaviours, and other intended and unintended consequences of the transition to permanent DST for adolescents.
Funded research examining changes at the population level is important to provide evidence about the effects of permanent DST for adolescents living in British Columbia.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
