Fatal accidents following changes in daylight savings time: the American experience

  • Published: Sleep Medicine Volume 2(1), 31-36, 2001
  • Authors: J. Varughese and R. P. Allen
  • Date Added: 18 Mar 2013
  • Last Update: 16 May 2014
  • Format: pdf


This study examines specific hypotheses that both sleep loss and behavioural changes occurring with the time shifts for Daylight Savings Time (DST) significantly effect the number of fatal RTIS in the United States of America.


Data from 21 years of United States’ fatal automobile RTIs were gathered. The mean number of RTIs on the days at the time of the shifts (Saturday, Sunday and Monday) was compared to the average of the corresponding mean number of RTIs on the matching day of the weeks preceding and following the shift. This was repeated for each DST shift. The number of RTIs for a particular shift was also correlated with the year of the RTIs.

Key Findings:

  • There was a significant increase in RTIs for the Monday immediately following the spring shift to daylight savings.

  • There was also a significant increase in number of RTIs on the Sunday of the Autumn shift from daylight savings.

  • No significant changes were observed for the other days.

  • A significant negative correlation with the year was found between the number of RTIs on the Saturdays and Sundays but not Mondays.

  • The sleep deprivation on the Monday following shift to daylight savings in the spring results in a small increase in fatal RTIs.

  • The behavioural adaptation anticipating the longer day on Sunday of the shift from daylight savings in the Autumn leads to an increased number of RTIs 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.

  • Public health educators should probably consider issuing warnings both about the effects of sleep loss in the spring shift and possible behaviours such as staying out later, particularly when consuming alcohol in the fall shift.

  • Sleep clinicians should be aware that health consequences from forced changes in the circadian patterns resulting from daylight savings come not only from physiological adjustments but also from behavioural responses to forced circadian changes.


Daylight savings, Short-term effects.


Discusses the short-term effects on the clock change in the Autumn. The research uses data from the US.