Abstract
The socio-cultural, industrial, and business demands of our current society require us to be active 24 hours a day, 7 days a week. This phenomenon implies working conditions that lead employees to perform their tasks in rotating shifts, during nighttime hours, and for extended shifts, thereby disrupting their biological rhythms, most fundamentally their sleep patterns. There is a need for naturalistic studies to evaluate the relationship between the specific design of work shifts and the actual amount of achievedsleep. To achieve this goal, we conducted a comprehensive study involving employees of the logistic chain of an oil company in Argentina. We compared three different types of work schedules that encompassed extended and rotating shifts work: 1) one in which workers completed two days of 12 h of daytime shifts followed by two consecutive 12 h night shifts, followed by four work-free days(“2x2x4x4x4” schedule), 2) one in which workers alternated four consecutive 12 h daytime shifts and four consecutive 12 h night shifts, flanked by four work-free days (“4x4x4” schedule), 3) and another, non-rotating, schedule involving continuous 12 h daytime shifts during 40 days, with no work-free days in between (“fixed 12h” schedule). Our study employed objective measurements such as wrist-actigraphy to record sleep patterns, temperature loggers to monitor peripheral temperature rhythms, as well as subjective self-reports regarding fatigue, somnolence, and psycho-affective features. In all cases, the duration of sleep during the resting period was significantly less than the recommended 7 hours of nocturnal sleep. The “2x2x4”schedule resulted in decreased sleep regularity and increased circadian disruption, associated with more nocturnal sleep time after diurnal work. Also, this shift exhibited higher levels of insomnia, increased fatigue impact, lower alertness levels, and heightened symptoms of depression. Our findings indicate that specific parameters vary depending on the type of schedule worked suggesting that, in practical terms, certain schedules are healthier and safer for these workers. These results provide valuable insights for the design of safer and healthier work schedules, with the potential to enhance worker well-being and overall productivity.