RT Journal Article SR Electronic T1 Early, but not late chronotypes, are up during their biological night when working the night shift JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 235 OP 235 DO 10.1136/oemed-2014-102572 VO 72 IS 3 A1 Vetter, Céline A1 Schernhammer, Eva S YR 2015 UL http://oem.bmj.com/content/72/3/235.1.abstract AB