Protocol for a prospective, multicentre, cross-sectional cohort study to assess personal light exposure.

Light profoundly impacts many aspects of human physiology and behaviour, including the synchronization of the circadian clock, the production of melatonin, and cognition. These effects of light, termed the non-visual effects of light, have been primarily investigated in laboratory settings, where light intensity, spectrum and timing can be carefully controlled to draw associations with physiological outcomes of interest. Recently, the increasing availability of wearable light loggers has opened the possibility of studying personal light exposure in free-living conditions where people engage in activities of daily living, yielding findings associating aspects of light exposure and health outcomes, supporting the importance of adequate light exposure at appropriate times for human health.

COPD 'diagnosis' based on spirometric reference equations.

Introduction: Chronic obstructive pulmonary disease (COPD) is suspected if the ratio between forced expired volume in 1 s (FEV(1)) and forced vital capacity is below 0.7 after bronchodilatation, according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD). As this ratio varies with age and gender, the lower limit of normality (LLN) of appropriate reference equations appears more adequate.