Interns admitted falling asleep during lectures, during rounds, and even during surgeries. Night shifts are associated with worse surgeon performance during laparoscopic surgeries. Practitioner risk factors include fatigue, depression, and burnout. Factors related to the clinical setting include diverse patients, unfamiliar settings, time pressures, and increased patient-to-nurse staffing ratio increases. Drug names that look alike or sound alike are also a problem. Errors in interpreting medical images are often perceptual instead of "fact-based"; these errors are often caused by failures of attention or vision. For example, visual illusions can cause radiologists to misperceive images. A number of Information Technology (IT) systems have been developed to detect and prevent medication errors, the most common type of medical errors. These systems screen data such as ICD-9 codes, pharmacy and laboratory data. Rules are used to look for changes in medication orders, and abnormal laboratory results that may be indicative of medication errors and/or adverse drug events. Examples Errors can include misdiagnosis or delayed diagnosis, administration of the wrong drug to the wrong patient or in the wrong way, giving multiple drugs that interact negatively, surgery on an incorrect site, failure to remove all surgical instruments, failure to take the correct blood type into account, or incorrect record-keeping. A 10th type of error is ones which are not watched for by researchers, such as RNs failing to program an IV pump to give a full dose of IV antibiotics or other medication. Errors in diagnosis According to a 2016 study from Johns Hopkins Medicine, medical errors are the third-leading cause of death in the United States. The projected cost of these errors to the U.S. economy is approximately $20 billion, 87% of which are direct increases in medical costs of providing services to patient affected by medical errors. Medical errors can increase average hospital costs by as much as $4,769 per patient. One common type of medical error stems from x-rays and medical imaging: failing to see or notice signs of disease on an image. The retrospective "miss" rate among abnormal imaging studies is reported to be as high as 30% (the real-life error rate is much lower, around 4-5%, because not all images are abnormal), and up to 20% of missed findings result in long-term adverse effects. A large study reported several cases where patients were wrongly told that they were HIV-negative when the physicians erroneously ordered and interpreted HTLV (a closely