Author Response: Early, But Not Late Chronotypes, Are Up During Their Biological Night When Working The Night Shift

We thank Drs Vetter and Schernhammer for their continuing interest in our work and their comments1 on our article.2 They interpret our findings differently than we do. Drs Vetter and Schernhammer suggest that the larger differences observed in melatonin secretion between early and late chronotypes indicate that early chronotypes are ‘more affected’ by night shift work than later chronotypes. We argue that since early compared to late chronotypes also had higher levels of melatonin during night work and night sleep, the time period when melatonin levels normally rise and peak …