Letter to the Editor Light Exposure and Melatonin among Rotating Shift Nurses—Letter

Grundy and colleagues (1) conducted a study into how light influencesmelatonin in nurses during rotating shifts. Inter alia, it was concluded that the examined "two-12-hour-days/two-12-hour-nights/5-days-off " pattern min-imally disrupts melatonin production. Interestingly, chronotype information was obtained but appeared to have negligible effects on shift-work–melatonin relation-ships. The authors suggest that "future studies that include chronotype are needed to confirm our results." But beyond "testing " particular study results, chronotype should be considered as a general candidate variable (2) in shift-work and health and disease research. With specific regard to melatonin, chronotype could nevertheless influence shift-work–light–melatonin rela-tionships but this may be detectable only after mor