Publication Date:
2015-02-14
Description:
Bhatti et al 1 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 levels than late chronotypes during daytime sleep after a nightshift. They also show a larger difference in melatonin secretion during their first regular night-time sleep after night shifts (table 3, dichotomous categorisation: =–34.6% and late types: =–4.2%), suggesting that early chronotypes are more affected by working night shifts than late chronotypes. This makes sense when considering the biological definition of chronotype, 2 where early chronotypes, with an earlier subjective, internal night, exhibit an earlier peak in melatonin secretion than late chronotypes.
Print ISSN:
1351-0711
Electronic ISSN:
1470-7926
Topics:
Medicine
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