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Adapting to Time Change Leads to Falls and other Health Risks

In the United States, Daylight Saving Time (DST) starts March 11, 2018. This change brings with it both personal and occupational health risks as individuals adjust to new daily cycles.

clock alarm on table

One third of countries have adopted some form of daylight saving time, and numerous published studies have confirmed the multitude of risks this change brings. The first is to the quality of sleep. A 2013 study among college students showed that advancing one hour resulted in a delay in their "get up time," an increase in the Time In Bed, Total Sleep Time, the Wake After Sleep Onset, the Mean Activity Score, and Wake Bouts, and a decrease In Sleep Efficiency.1

Another study,2 conducted in Australia, showed that the time change impacted when and if people were active. About 45 percent of the cohort reported that daylight saving time had affected when they were physically active: fewer people exercised in the morning and more exercised in the evening. Analyzed at the individual level, almost a quarter of the cohort ceased to exercise in the morning and a similar percentage exercised in the evening only during DST. There was also an overall reduction in the average number of daily exercise sessions, with 8 percent not exercising at all during DST (October to April).

The power of policy to influence behaviour change: daylight saving and its effect on physical activity

clock alarm on table

Time of day of physical activity: Prevalence during the most recent summer, prior to, during and following the daylight saving period. (Click on image for larger version.)

Changing to DST results in greater safety and health risks as people anticipate and then adapt to the change—all of which have been attributed to changes in sleep duration/quality and circadian misalignment. A study3 of data from 12.6 million accident claims over 11 years in New Zealand showed that road accidents are 16 percent higher the first day after the time change, 12 percent higher the second day after, and then decrease over time. Work accidents, though having limited impact, decline in the week after the start of DST, with Friday being 13 percent lower than at the beginning of the week. In contrast, anticipating the change, home accidents and falls decline just prior to DST and rise just before standard time starts. Separately, studies4 also found that the incidence of myocardial infarction was significantly higher for the first three weekdays after the transition to DST. In contrast, after the transition out of DST, only the first weekday was affected significantly.

Clinicians too directly experience the impact of time change on patient behavior. A study published in Chronobiology International showed that the number of missed medical appointments significantly increased the first week of DST. This trend reversed during the transition period back to standard time.

In addition to the studies noted above that reflect the temporary impact of time change, sleep health is a recognized factor correlating with the development of numerous diseases including obesity, cardiovascular disease, cancer, emotional distress and impaired learning. Being able to offer a formal sleep prescription to help patients get a better night’s sleep and coaching patients on behavior change may help patients make this adjustment to DST and with long-term health and disease prevention. Extensive information on sleep health and coaching is just part of what is offered in the online Lifestyle Medicine Core Competencies Program. More information about the program and other lifestyle medicine offerings is on the ACPM website.

  1. Effects of Transitions into and out of Daylight Saving Time on the Quality of the Sleep/Wake Cycle: an Actigraphic Study in Healthy University Students. Chronobiology International. 2013 Dec;30(10):1218-22.
  2. The power of policy to influence behaviour change: daylight saving and its effect on physical activity. Australian and New Zealand Journal of Public Health. 2010 Feb;34(1):83-8.
  3. Accident rates and the impact of daylight saving time transitions. Accident Analysis & Prevention. 2018 Feb;111:193-201.
  4. Missed medical appointments during shifts to and from daylight saving time. Chronobiology International. 2017 Dec 28:1-5.
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