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Early, but not late chronotypes, are up during their biological night when working the night shift
  1. Céline Vetter1,2,
  2. Eva S Schernhammer1,2
  1. 1Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
  2. 2Harvard Medical School, Harvard University, Boston, Massachusetts, USA
  1. Correspondence to Dr Céline Vetter, Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard University, 181 Longwood Ave, Boston, MA 02115 USA; celine.vetter{at}

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Bhatti et al1 recently examined the impact of chronotype on melatonin levels in shift-workers and concluded that ‘(…) morning type shift-workers were better able to maintain normal patterns of melatonin secretion (…), suggesting that morning types may be protected against the negative effects of shift-work related melatonin disruption’. However, their data show that, compared to daytime workers sleeping at night, early chronotypes have lower melatonin …

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  • Contributors CV wrote the first draft of the letter and ESS and CV both further edited it.

  • Competing interests None.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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