57 Literature review about the effects of chemical exposure to lead and cadmium in the sleep-wake cycle

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The world of work has undergone significant changes, with the adoption of new technologies and the use of various chemicals and minerals in their processes and production methods, expanding and increasing the environmental hazards. A bibliographic survey about deleterious effects on exposure to the chemicals lead and cadmium was conducted in order to verify how this exposure may influence the population’s sleep-wake cycle.


This is an exploratory study through open access literature review, of systematic type. Search was conducted in the period from 2001 through October 2016. Search strategy has included the use and combination of descriptors and terms: Chemical Exposure; Exposure to Metals; Exposure to Lead; Exposure to Cadmium; Sleepiness; Sleep Disorders; Sleep Disturbances; Sleep-Wake Cycle.


Twenty-nine studies have been found from the referred theme. Several studies have been performed in animal models. Only three papers reported the effects of metals on sleep-wake cycle. The first one was carried out with a population living in the surroundings of a metal recycling plant, where authors have detected that the exposed population had 2.3 chances to report sleep complaints. The other two studies observed children and pre-teens with high levels of lead in the blood have been associated to delay in the onset of sleep, longer duration of nocturnal awakenings, shorter duration of sleep, insomnia (OR=2.01) and longer daytime sleepiness (OR=2.90).


There are effects which link the environmental exposure to lead and cadmium with sleep complaints. Considering there are several production sectors, such as mining, and manufacturing processing industries that work with such metals and whose workers are in continuous shifts, it is likely that workers in these industries may suffered the effects of metal exposure and those leading to changes in biological rhythms caused by shift work. Financial Support: Faperj (E-10/225.935/2016).

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