Twenty-First Century: The 24/7 Society as an Environmental Mutation
The main reason for the reduced levels of sleep we see in the modern 24/7 society has been the artificial lighting that lights up our evenings. Longitudinal and transversal epidemiologic studies indicate that the number of daily hours of sleep has fallen since 1960 to date from 8 to 6 h. A particular group of intrinsically photosensitive retinal ganglion cells containing a primitive photopigment, melanopsin, are photoreceptors that allow adjustments of the biological clock. Artificial light striking the retina from dusk until dawn exerts a strong inhibitory activity of hypothalamic neurons that induce sleep and a strong excitatory activity of brain mechanisms that maintain wakefulness. A suppression of the nocturnal release of melatonin occurs. The distribution of sleep disorders as a function of socioeconomic status indicates that the very low socioeconomic stratum had a higher percentage of subjects with poor quality of sleep and daytime sleepiness. Shift work disorder is increasingly found among several groups of workers. Over 10 % of night workers and rotating workers met criteria for a shift work disorder. There are major individual differences in susceptibility to shift work disorder, and susceptibility can lead to accidents and comorbidity, including metabolic syndrome, ischemic heart disease, and cancer. Among guidelines for effective management of shift work disorder, appropriately timed bright light treatment has proven helpful in assisting in phase shifts. Planned napping just before or on the job combined with caffeinated drinks has been reported to reduce sleepiness and improve alertness while working. Melatonin (2–3 mg) is effective at promoting daytime sleep, both by causing sleepiness and by inducing phase shifting. The only way to solve sleep deprivation is to sleep. In general, after sleep deprivation one-third of the total lost sleep time, 100 % of slow-wave sleep, and 30–50 % of rapid eye movement (REM) sleep are recovered. Therefore, the estimated 10 h of sleep deficit accumulated during the week can be recovered by sleeping about 90 min more daily on weekends.
Keywords24/7 Society Barómetro de la Deuda Social Argentina Cancer Hyperactivity/attention deficit disorder LEDs Non-24-h sleep/wake disorder Napping Shift work disorder Short- and long-distance drivers Sleep in slum dwellers
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