The extra sunlight should generate enough vitamin D to boost immunities and send the winter blues away but according to various researchers and even governments, transitioning to daylight savings time is unhealthy and deadly due to the impact on chronobiological rhythms.
Here is an international roundup of scientific studies and government findings on the effects of springing forward:
In 2005, Kazakhstan stopped springing forward because of health concerns, after finding the negative impact on "children's and senior citizens' health" and that the change "caused a rise of diseases, traffic accidents and industrial injuries as well." A national survey concluded that, "51.6% of Kazakhstani citizens responded badly to daylight-saving observation." Article, "Kazakhstan canceled shifting to the "summer" and "winter" time": http://engnews.gazeta.kz/art.asp?aid=56924
A 2008 research study in the New England Journal of Medicine found heart attacks increase 4% during the first three workdays after springing forward. "These transitions can disrupt chronobiologic rhythms and influence the duration and quality of sleep, and the effect lasts for several days after the shifts," and that the effect that is "more pronounced in men than in women." Study, "Shifts to and from Daylight Saving Time and Incidence of Myocardial Infarction": http://content.nejm.org/cgi/reprint/359/18/1966.pdf
Australian suicide data over 30 years confirmed that "male suicide rates rise in the weeks following the commencement of daylight saving, compared to the weeks following the return to eastern standard time and for the rest of the year". Researchers concluded, "small changes in chronobiological rhythms are potentially destabilizing in vulnerable individuals." Study, "Small shifts in diurnal rhythms are associated with an increase in suicide: The effect of daylight saving": http://www3.interscience.wiley.com/journal/119419743/abstract?CRETRY=1&SRETRY=0
In Sweden and United States researchers have found that there is an increase in driving-related accidents due to lack of sleep and or driving at later hours. The Swedish study found there were 11% more accidents after the time change.
"Fatal accidents following changes in daylight savings time: the American experience": http://www.ncbi.nlm.nih.gov/pubmed/11152980
"The shift to and from daylight savings time and motor vehicle crashes" in Sweden: http://www.ncbi.nlm.nih.gov/pubmed/10868764
In 2000, researchers found a link between changes in sleeping patterns and "large negative returns on financial indices" after springing forward on a weekend.
"Losing Sleep at the Market: The Daylight Savings Anomaly": http://www.jstor.org/pss/117321?cookieSet=1
Plan for a healthy spring forward, make sure you know when your clocks are changing, do not stress about it, and if you are sensitive to changing your sleep patterns consider taking a few vacation days or starting your day later no matter what your clock, watch or smartphone says. Since the date for springing forward is different from nation to nation, here is a list so you can also be polite when ringing friends and family around the world: http://www.timeanddate.com/time/dstevents.html