Effects+of+Daylight+Saving+Time+(DST)

toc  [|Daylight Saving Time (DST)] is a practice that has become commonplace in approximately 70 countries worldwide affecting over 1 billion people [1]. In the United States DST initially began during WWI and has been consistently present in some form since World War II [1]. Through the years it has been extended and the dates it begins and ends modified. Currently, DST begins in mid-March and continues until the beginning of November, roughly 7 ½ months.

Each year as the time changes approach, there are newspaper articles and news reports attributing numerous physiological and psychological effects to DST [2] [3] [4]. Some research suggests the transition to and from DST leads to insomnia and sleep disturbances, depression and suicide, heart attacks and strokes, traffic accidents, emergency room visits, and lower standardized test scores. Other research refutes those findings and contends that the benefits to the added daylight outweigh the disadvantages of the time change. This article will look at the pros and cons of Daylight Saving Time as it affects the health and well-being of people undergoing the time transition each spring and fall.

=Circadian Rhythms =

 [|Circadian rhythms] are the physical, mental and behavioral changes that occur in most living things, including plants and animals, during a 24-hour cycle [5]. Circadian rhythms also regulate seasonal changes such as bird migration, animal hibernation, and plant changes. In humans, circadian rhythms influence sleep-wake cycles, hormone release, regulation of body temperature and other bodily functions [6].The study of circadian rhythms is called [|chronobiology]. A disturbance in an individual’s circadian rhythm - setting the clocks forward or backward, traveling across time zones, even staring at a computer screen late at night - can cause physical and psychological issues such as sleep disorders, obesity, depression, bipolar disorder and [|seasonal affective disorder (SAD)] [7].

According to the [|National Institute of General Medical Sciences], circadian rhythms are not the same things as ‘biological clocks,’ but our biological clocks drive our circadian rhythms [5]. Circadian rhythms are not only produced internally ([|endogenous]), but are also affected ([|entrained]) by external or environmental factors ([|zeitgebers]) [8]. The body’s circadian rhythm is extremely sensitive to light [9]. Circadian clocks use daylight to synchronize (entrain) to an organism’s environment and humans will adjust to east-west progression of dawn in a given time zone [10]. When that entrainment is altered, such as a transition to DST which does not use an environmental cue (dawn), human circadian systems have difficulty making the adjustment [10].

=Physical Manifestations =

Sleep Disorders
There have been numerous studies linking the transition to DST to [|sleep disorders], including insomnia and fragmented sleep. In the time period following the switch to DST, sleep duration was found to be reduced by more than an hour and sleep efficiency was reduced by 10% [11]. Transitions between DST and [|Standard Time (ST)] increase nighttime restlessness and interfere with the quality of an individual’s sleep, which could negatively affect mood [12]. There is also evidence that the adjustment to the time change may take up to six days or more resulting in a cumulative effect of [|sleep deprivation] making people more prone to accidents, daytime fatigue, poor concentration and overeating [13].

Studies found that the adjustment to DST is particularly difficult for individuals who habitually sleep less than 7 ½ hours [13] and for those who are more “night owls” rather than “morning people” [12][14]. Additionally, the transition exacerbates symptoms in individuals with prior mood or sleep disorders [12]. Researchers also found the change in the sleep-wake cycle is more affected by the spring transition where individuals ‘lose’ an hour of sleep, than by the autumn transition where clocks are set back one hour [12].

Other studies have determined that the effect is fairly short lived, with individuals adjusting to the time transition in as little as two days [15].

Ischemic Stroke
Studies have found that there is a greater risk of [|ischemic stroke] during the first two days after DST transition. This increase in the risk for stroke is likely related to interrupted sleep patterns and the associated disruption to circadian rhythms [16]. This risk is even higher in certain groups such as those with malignancies and elderly individuals. The increased risk did not differ between turning clocks back or turning them forward suggesting that the body reacts to both changes [17].

Heart Attacks
An increased incidence of [|Acute Myocardial Infarction (AMI)], or heart attacks, has been reported after DST [18] [19]. Similarly, research has linked heart attacks to not getting enough sleep [18]. Evidence suggests that even modest sleep deprivation and disturbances in the sleep-wake cycle might increase the risk of AMI across the population. Again, subgroups such as the elderly are at a higher risk [20].

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Accidents
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">A study in 2016 positively linked an increase in fatal automobile crashes following DST. This research found the correlation to be less tied to the absence of ambient light, and more attributable to sleep deprivation following DST [21]. The results of this study conflict with a 1995 study that found that fatal automobile crashes were directly related to daylight, whether that change in daylight was attributable to DST or to seasonal changes [22]. The 1995 study suggested that 901 fewer fatal crashes might have occurred if DST had been retained year-round from 1987 to 1991 [22]. However, another study looked at accident reporting one week before and one week after DST for a 25-year period, 1981 to 2006, and found no increase in the number of traffic accidents [23]. Similar results were found in Minnesota, finding no noticeable increase in accidents attributable to DST [24].

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">In addition to automobile accidents, one study suggests there is an overall occupational safety issue related to DST. Using [|Mine Safety and Health Administration] data, researchers found that on average there were 3.6 more injuries on the Monday following the DST transition as compared to other Mondays. This increase led to a loss of 2,649 days of work, suggesting that the injuries were severe [25].

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Detrimental Effect on Standardized Test Scores
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">A study based in Indiana found there was a significant negative relationship between the transition to DST and the [|SAT] scores of high school students. In this particular state, researchers found that there was a 16.4-point difference in SAT scores following the imposition of DST. [26] There is a direct correlation between sleep deprivation following DST and school performance, including the taking of standardized tests. DST time especially affected older students and students who typically were accustomed to late nights [27]. The evidence suggests that the disruption of the sleep cycles of children and teens can be detrimental to their overall scholastic performance.

=<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;"> Psychological Manifestations =

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Depression
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">In addition to sleep disturbances, there is also a correlation between the DST transition and [|depression]. Numerous studies have found a direct connection between the amounts of sunlight an individual gets and depressive episodes [28] [29]. Some people who are deprived of sunlight acquire [|Seasonal Affective Disorder (SAD)], a mood disorder triggered by shortened daylight hours [30].

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">A study based in Denmark found that the number of depression diagnoses increased by 8% immediately after the transition from DST [31]. Other studies have reached similar results showing an increased incidence of depressive episodes with the time transition [32]. The Danish study found the lack of sunlight in the evenings may trigger this negative psychological effect. The depression dissipated over approximately 10 weeks. It also indicated that the depression was more directly tied to the transition in the spring rather than the fall [31].

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">A Finnish study, however, refuted any connection between DST and an increase in incidents of manic episodes for the two weeks before and the two weeks after the transitions. Reviewing hospital records for a 16-year period (1987-2003), they found no evidence to support an increase in manic episodes following the time change [24].

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Suicide
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">An Australian study looked at suicide data from 1971 to 2001 to determine if there was a link between suicide and DST. The data confirmed that male suicide rates rose in the weeks following the commencement of DST as compared to the weeks following the return to standard time [32]. This research determined that even small shifts in [|diurnal rhythms] can have a destabilizing effect in vulnerable individuals [32].

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">General Life Satisfaction
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Overall, there is evidence that DST transition had a significant negative effect on general life satisfaction and mood due to the stress and anxiety brought on by the time change. This was especially true for individuals who had little flexibility in their work schedules. [33] This study infers that the inability to get accustomed to the time change gradually caused added stress for those who had to be at work or school at a specified time following the change.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">However, proponents argue that the health benefits of the extra hour of daylight outweigh the negative aspect of DST. The increase in daylight hours gives people more opportunity to get outdoors, increasing the amount of exercise and exposure to the sun which are both positive health benefits [34].

=<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Conclusion =

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">There appears to be sufficient empirical evidence that the transitions each year from Daylight Saving Time and back create changes to our circadian rhythms. In turn, those changes could affect our health in many detrimental ways including disruption of sleep, changes in mood and behavior, and fatigue. In the worst cases, the time transition can lead to more serious health consequences such as heart attacks and strokes, traffic accidents and serious depression.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Although there are many proponents of DST, there should be continued research on the potential impacts to health. It is important to realize what the effects may be for some individuals and how those effects may be anticipated and diminished.

=<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">References =

<span style="font-family: Arial,Helvetica,sans-serif;">[1] Kotchen, Matthew J. and Laura E. Grant. 2011. “Does Daylight Saving Time Save Energy? Evidence From a Natural Experiment in Indiana.” The Review of Economics and Statistics, Nov 2011, Vol. 93, No. 4, Pages 1172-1185. doi:10.1162/REST_a_00131

<span style="font-family: Arial,Helvetica,sans-serif;">[2] Borreli, Lizette. 2016. “Daylight Saving Time." 2016 Health Pros And Cons, From Extra Hour of Sleep to Cluster Headaches.” The Grapevine. Nov 4, 2016. http://www.medicaldaily.com/daylight-saving-time-2016-health-pros-and-cons-extra-hour-sleep-cluster-403577

<span style="font-family: Arial,Helvetica,sans-serif;">[3] Poppick, Laura. 2013. “5 Weird Effects of Daylight Saving Time.” 2013. Live Science. Nov 2, 2013. http://www.livescience.com/40903-daylight-saving-time-affects-your-body.html ???

<span style="font-family: Arial,Helvetica,sans-serif;">[4] Berman, Ali. 2015. “7 Little-Known Side Effects of Daylight Saving Time.” Mother Nature Network. Nov 2, 2015. <span style="font-family: Arial,Helvetica,sans-serif;">[]

<span style="font-family: Arial,Helvetica,sans-serif;">[5] “Circadian Rhythms Fact Sheet.” 2012. National Institutes of Health - National Institute of General Medical Sciences. https://www.nigms.nih.gov/Education/pages/Factsheet_CircadianRhythms.aspx

<span style="font-family: Arial,Helvetica,sans-serif;">[6] Carlson, Emily, Alisa Machalek, Kirstie Saltsman, Chelsea Toledo. 2012. “Tick Tock: New Clues About Biological Clocks and Health.” National Institutes of Health - National Institute of General Medical Sciences. https://publications.nigms.nih.gov/insidelifescience/biological-clocks.html

<span style="font-family: Arial,Helvetica,sans-serif;">[7] Carlson, Emily. 2014. “Resetting our Clocks: New Details About How the Body Tells Time.” National Institutes of Health - National Institute of General Medical Sciences. Updated 3/6/2014. <span style="font-family: Arial,Helvetica,sans-serif;">[]

<span style="font-family: Arial,Helvetica,sans-serif;">[8] Monk, T. H. 2010. ‘Enhancing Circadian Zeitgebers.”.Sleep, 33(4), 421–422. <span style="font-family: Arial,Helvetica,sans-serif;">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2849779/

<span style="font-family: Arial,Helvetica,sans-serif;">[9] Shanahan, Theresa L., Jamie M. Zitzer, Charles A Czeisler. 1997. “Resetting the Melatonin Rhythm with Light in Humans.” Journal of Biological Rhythms, Vol. 12, No. 5, Dec 1997, 556-657

<span style="font-family: Arial,Helvetica,sans-serif;">[10] Kantermann, Thomas, Myriam Juda, Martha Merrow, and Till Roenneberg. 2007. "The Human Circadian Clock's Seasonal Adjustment Is Disrupted by Daylight Saving Time." Current Biology 17, no. 22: 1996-2000. Academic Search Premier, EBSCOhost

<span style="font-family: Arial,Helvetica,sans-serif;">[11] Lahti, Tuuli A., Sami Leppämäki, Jouko Lönnqvist, Timo Partonen. 2006. “Transition to Daylight Saving Time Reduces Sleep Duration Plus Sleep Efficiency of the Deprived Sleep.” Neuroscience Letters, Volume 406, Issue 3, 9 <span style="font-family: Arial,Helvetica,sans-serif;">Oct 2006, 174-177, ISSN 0304-3940, http://dx.doi.org/10.1016/j.neulet.2006.07.024.

<span style="font-family: Arial,Helvetica,sans-serif;">[12] Lahti, Tuuli Al. Sami Leppamaki, Jouko Lonnqvist, and Timo Partonen. 2008. “Transitions Into and Out of Daylight Saving Time Compromise Sleep and the Rest-Activity Cycles.” BMC Physiology, 8:3. Doi: 10.1186/1472-6793/8/3

<span style="font-family: Arial,Helvetica,sans-serif;">[13] Harrison, Yvonne. 2013. "Individual Response to the End of Daylight Saving Time is Largely Dependent on Habitual Sleep Duration." Biological Rhythm Research 44, no. 3: 391-401. Academic Search Premier, EBSCOhost.

<span style="font-family: Arial,Helvetica,sans-serif;">[14] Tonetti, Lorenzo, Alex Erbacci, Marco Fabbri, Monica Martoni, and Vincenzo Natale. 2013. "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: The Journal Of Biological & Medical Rhythm Research 30, no. 10: 1218-1222. Academic Search Premier, EBSCOhost (accessed November 28, 2016).

<span style="font-family: Arial,Helvetica,sans-serif;">[15] Valdez, Pablo, Candelaria Ramírez, and Aida García. 2003. "Adjustment of the Sleep-Wake Cycle to Small (1-2h) Changes in Schedule." Biological Rhythm Research 34, no. 2: 145. Academic Search Premier, EBSCOhost.

<span style="font-family: Arial,Helvetica,sans-serif;">[16] Foerch, Christian MD, Horst Werner Korf MD, Heluth Steinmetz MD, Matthais Sitzer,MD. 2008. “Abrupt Shift of the Pattern of Diurnal Variation in Stroke Onset With Daylight Saving Time Transitions.” Circulation Jun 2008, 118:3, 284-290 <span style="font-family: Arial,Helvetica,sans-serif;">DOI: 10.1161/circulationaha.108.771246

<span style="font-family: Arial,Helvetica,sans-serif;">[17] Anderson, Pauline. 2016. “Daylight Saving Time Switch May Boost Stroke Risk.” Medscape. Mar 9, 2016. http:www.medscape.com/viewarticle/860109_print

<span style="font-family: Arial,Helvetica,sans-serif;">[18] Jiddou, Monica R., Mark Pica, Judy Boura, Lihua Qu, Barry A. Franklin. 2013. “Incidence of Myocardial Infarction With Shifts To and From Daylight Savings Time.” The American Journal of Cardiology, 111.5 (Mar 1, 2103); 631-635. <span style="font-family: Arial,Helvetica,sans-serif;">http://dx.doi.org/10.1016/j.amjcard.2012.11.010.

<span style="font-family: Arial,Helvetica,sans-serif;">[19] Janzsky, Imre, Staffan Ahnve, Rickard Ljung, Kenneth J. Mukamal, Shiva Gautam, Lars Wallentin, Ulf Stenestrand. 2011. “Daylight Saving Time Shifts and Incidence of Acute Mycardial Infarction.” Sleep Medicine, 13 (2012): 237-242. <span style="font-family: Arial,Helvetica,sans-serif;">Doi: 10.2016/j.sleep.2011.07.019

<span style="font-family: Arial,Helvetica,sans-serif;">[20] Sandhu A, Seth M, Gurm HS. 2014. “Daylight Savings Time and Myocardial Infarction.” Open Heart, 2014;1. doi:10.1136/openhrt-2013- 000019

<span style="font-family: Arial,Helvetica,sans-serif;">[21] Smith, Austin C. 2016. “Spring Forward at Your Own Risk: Daylight Saving Time and Fatal Vehicle Crashes.” American Economic Journal: Applied Economics, 8(2): 65-91. []

<span style="font-family: Arial,Helvetica,sans-serif;">[22] Ferguson, Susan A., David F. Preusser, Adrian K. Lund, Paul L. Zador, Robert G. Ulmer. 1995. “Daylight Saving Time and Motor Vehicle Crashes: The Reduction in Pedestrian and Vehicle Occupant Fatalities.” American Journal of Public Health, Vol. 85, No.1: 92-95

<span style="font-family: Arial,Helvetica,sans-serif;">[23] Lahti, Tuuli A., Jari Haukka, Jouko Lonnqvist, and Timo Partonen. 2008. Daylight Saving Time Transitions and Hospital Treatments Due to Accidents or Manic Episodes. BMC Public Health, 8:74. DOI: 10.1186/1471-2458-8-74

<span style="font-family: Arial,Helvetica,sans-serif;">[24] Huang, Arthur, and David Levinson. 2010. "The Effects Of Daylight Saving Time On Vehicle Crashes In Minnesota." Journal Of Safety Research 41, no. 6: 513-520. Academic Search Premier, EBSCOhost.

<span style="font-family: Arial,Helvetica,sans-serif;">[25] 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. []

<span style="font-family: Arial,Helvetica,sans-serif;">[26] Gaski, J. F., & Sagarin, J. 2011. “Detrimental Effects of Daylight-Saving Time on SAT Scores.” Journal of Neuroscience, Psychology, and Economics, 4(1), 44-53. []

<span style="font-family: Arial,Helvetica,sans-serif;">[27] Schneider, Anne-Marie Schneider, Christoph Randler. 2009. “Daytime Sleepiness During Transition into Daylight Saving Time in Adolescents: Are Owls Higher at Risk?” Sleep Medicine, 10:9, 1047-1050. [].

<span style="font-family: Arial,Helvetica,sans-serif;">[28] “Depression; Sunlight And Serotonin Underlie Seasonal Mood Disorders.” (2003). Pain & Central Nervous System Week,, 15. Retrieved fromhttps://colorado.idm.oclc.org/login?url=http://search.proquest.com.colorado.idm.oclc.org/docview/208456124?accountid=14503

<span style="font-family: Arial,Helvetica,sans-serif;">[29] Hadlow, Narelle C. Suzanne Browne, Robert Wardrop, and David Henley. 2013. “The Effects of Season, Daylight Saving and Time of Sunrise on Serum Cortisol in a Large Population.” Chronobiology International, 2014, 31(2): 243-251. DOI: 10.3109/07420538.2013.8444162

<span style="font-family: Arial,Helvetica,sans-serif;">[30] Sanassi, Lorraine A. 2014. “Seasonal Affective Disorder: Is There Light at the End of the Tunnel?” Journal of the American Academy of Physician Assistants, 27:2, 18-22. Doi: 10.1097/01.JAA.0000442698.3223.f3

<span style="font-family: Arial,Helvetica,sans-serif;">[31] Hansen, Bertel T., Kim M Sonderskov, Ida Hageman, Peter T. Dinesen, Soren D Ostergaard. “”Daylight Savings Time Transitions and the Incidence of Unipolar Depressive Episodes.” 2016. Epidemiology, Nov 3, 2015. Doi: 10.1097/EDE.0000000000000580

<span style="font-family: Arial,Helvetica,sans-serif;">[32] Berk, Michael, Seetal Dodd, Karen Hallam, Lesley Berk, John Gleeson, and Margaret Henry. 2008. "Small Shifts In Diurnal Rhythms Are Associated With An Increase In Suicide: The Effect Of Daylight Saving." Sleep & Biological Rhythms, 6, No. 1: 22-25. Academic Search Premier, EBSCOhost

<span style="font-family: Arial,Helvetica,sans-serif;">[33] Kountouris, Yiannis, Kyriaki Remoundou. 2013. “About Time: Daylight Saving Time Transition and Individual Well-Being.” Economics Letters, 122 (2014), 100-103. []

<span style="font-family: Arial,Helvetica,sans-serif;">[34] Gander, Kashmira. 2016. “The Health Impact of Daylight Savings Time.” The Independent (Daily Edition): 21. London (UK): Independent Digital News & Media (Mar 27, 2016). []

=<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Hyperlinks =


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">[|Daylight Saving Time]
 * 2) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 14.300000190734863px;">[|Standard Time (ST)]
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">[|Circadian Rhythm]
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">[|Chronobiology]
 * 5) <span style="font-family: Arial,Helvetica,sans-serif;">[|Endogenous]
 * 6) <span style="font-family: Arial,Helvetica,sans-serif;">[|Entrained]
 * 7) <span style="font-family: Arial,Helvetica,sans-serif;">[|National Institute of General Medical Sciences]
 * 8) <span style="font-family: Arial,Helvetica,sans-serif;">[|Zeitgeber]
 * 9) <span style="font-family: Arial,Helvetica,sans-serif;">[|Seasonal Affective Disorder]
 * 10) <span style="font-family: Arial,Helvetica,sans-serif;">[|Sleep disorders]
 * 11) <span style="font-family: Arial,Helvetica,sans-serif;">[|Ischemic stroke]
 * 12) <span style="font-family: Arial,Helvetica,sans-serif;">[|Acute Myocardial Infarction]
 * 13) <span style="font-family: Arial,Helvetica,sans-serif;">[|Sleep deprivation]
 * 14) <span style="font-family: Arial,Helvetica,sans-serif;">[|Mine Safety and Health Administration]
 * 15) <span style="font-family: Arial,Helvetica,sans-serif;">[|SAT]
 * 16) <span style="font-family: Arial,Helvetica,sans-serif;">[|Depression]
 * 17) <span style="font-family: Arial,Helvetica,sans-serif;">[|Diurnal Cycle]