Daylight Saving Time Health Advisory

The practice of abruptly setting clocks ahead by one hour from spring until fall, called daylight saving time (DST), was first instituted in Europe in 1916 to decrease use of energy-consuming incandescent lighting by extending the evening natural daylight hours. This practice afterwards became widespread peacetime policy in the United States in 1966. Subsequent studies of the actual economic effects of DST show variable benefits or disadvantages across different business sectors, and the economic costs or benefits of DST where it is practiced are debated.

While the commercial effects of DST remain contested, the sudden change in clock time has an untoward effect on sleep duration and quality. Studies are consistent in showing that with DST changes, there is sleep disruption. This disruption in sleep/wake patterns manifests as a decrease in total sleep time and sleep quality, and in some studies, decrements in daytime measures of cognition. Reports on the effects of DST on vehicular accident rates vary across studies, but give ample cause for concern.

Taken together, studies regarding the sleep health effects of DST show:

  1. Moving into or out of DST has adverse effects on sleep/wake patterns that last about 5-7 days, and
  2. The effects of changing to DST are probably most notable for those who enter the change with insufficient sleep.

Adequate duration and good quality sleep are necessary for optimal health. Because of the adverse effects of DST on sleep, the American Academy of Sleep Medicine advises that adults obtain at least 7 hours of sleep per night preceding and following DST changes. Graduated adjustment of sleep and wake times beginning 2-3 days before DST can also help with this transition. When performing activities that require maximal alertness, individuals also should exercise particular caution for at least 7 days following DST changes.

Adopted by the AASM Board of Directors: March 3, 2016