Switching to and from Daylight Saving Time (DST) – setting the clock forward or backward a single hour – may not sound like a big deal, but there’s a reason why our sleep-wake cycle is called a circadian rhythm. Even the slightest disruption can have a long-lasting domino effect on your whole routine, similar to a drummer messing up the rhythm of a song.
Sleep experts always emphasize the importance of a consistent sleep schedule. That consistency winds up your body’s internal clock practically every night, making it harder and harder to adjust it, as you would an actual watch upon “spring forward” or “fall back.”
Studies have validated this problem by pinpointing its immediate effects on us on the dreaded Monday after DST.
Monday after “spring forward”
One study found that “on Mondays directly following the switch DST, workers sleep on average 40 min less than on other days.”  Forty minutes may not sound like a big deal, but to someone who’s already sleep-deprived, which according to different statistics is from 11% of Americans to one in every three, this can be the last straw.
And the last straw can be a dangerous thing.
Another study that focused on the Monday after spring forward found a “significant increase” in traffic accidents and a “small increase” in fatal ones. Interestingly, the reverse shift, from DST to Standard Time, can be tricky as well.
“The behavioral adaptation anticipating the longer day on Sunday of the shift from DST in the fall leads to an increased number of accidents, suggesting an increase in late night (early Sunday morning) driving, when traffic related fatalities are high, possibly related to alcohol consumption and driving while sleepy.”
Some experts believe the effects of shifting to and from DST can last long after that infamous Monday “after.”
“It’s not one hour twice a year. It’s a misalignment of our biologic clocks for eight months of the year,” says Beth Ann Malow, MD, Burry Chair in Cognitive Childhood Development, and professor of Neurology and Pediatrics in the Sleep Disorders Division at Vanderbilt University Medical Center. 
This sums up the point of her commentary, published in JAMA Neurology, in which she and her colleagues reference a body of research to argue against DST altogether.
Different people are affected differently by DST, which depends on the natural adaptability and flexibility of their sleeping habits.
But there are universal steps all people can take to smoothen these time transitions and make them more gradual, such as waking up 15-20 minutes earlier for 2-3 days before the actual time change, getting more natural light exposure, as soon as possible after waking up, as it signals the body it’s time to be awake, and resist the urge to take long naps that exacerbate the circadian misalignment.
- Barnes, C. M., & Wagner, D. T. (2009). Changing to daylight saving time cuts into sleep and increases workplace injuries. Journal of Applied Psychology, 94(5), 1305–1317.
- Varughese and Allen, Fatal accidents following changes in daylight savings time: the American experience, Sleep Med 2001 Jan;2(1):31-36, Impact Factor= 10,517, Times Cited = 101
- Beth A. Malow, Olivia J. Veatch, Kanika Bagai. Are Daylight Saving Time Changes Bad for the Brain?JAMA Neurology, 2019, Impact Factor = 13.608; Times Cited = 7
Image Credits: Wikimedia Commons