Daylight saving time and myocardial infarction: should we be worried? A review of the evidence.

Transitions into and out of Daylight Saving Time (DST) may disrupt circadian rhythms and lead to sleep disturbance and deprivation. A first report observed an association between DST and acute myocardial infarction (AMI), especially after the spring shift and in women. We tried to identify and evaluate the possible association between DST and AMI, using the MEDLINE, EMBASE and Google Scholar electronic database (years 2009-2016), with regards to the searching terms 'daylight saving time', 'daylight saving time' plus 'gender', and 'daylight saving time' plus 'acute myocardial infarction'. In total, 72, 10, and 6 studies were found, respectively. Overall, 6 studies, including a total of 87,994 cases, resulted to satisfy the searching request, and were included in the present analysis. All studies confirmed a higher occurrence of AMI in the spring shift, ranging from 4 to 29%, whereas only 1 study showed a higher occurrence of AMI in the autumn shift. By the way, in 5 studies providing separate analysis, the results by sex were not univocal. In fact, as for the spring shift, 2 studies did not show differences between men and women, 2 reported a higher frequency in men, and 1 in women. Regarding the autumn shift, only 1 study reported a higher occurrence of AMI in women. These results support the presence of an association between DST and a modest increase of AMI occurrence, especially for the spring shift, and with no definite gender specific differences.