According to a new study published in journal Neurosurgery, it has been revealed that patients who undergo a neurosurgical procedure with surgical start times between 9 pm and 7 am, are at an increased risk of developing complications compared to patients with a surgical start time earlier in the day. The scientists analyzed all 15,807 patients undergoing neurological surgery between 2007 and 2014 in the University of Michigan Health System of which 785 complications were identified through the self-reported morbidity and mortality reports created by faculty and resident neurosurgeons. The odds of a complication were increased by more than 50% for procedures with start times between 9 pm and 7 am. The only statistically significant factor that predicted the severity of the complication was if the operation was an emergency compared to an elective surgery. A patient's odds of having a surgical complication increased significantly between 9 pm and 7 am even after accounting for whether the case was an emergency versus elective procedure or if the patient had co-morbid conditions. When accounting for the length of the surgery, the odds of a complication more than doubled.