In recent years, as a response to social and economic demands, the so-called ’24-h society’ has dramatically evolved and expanded. According to surveys in European countries, the USA and also in developing countries, approximately 20% of employees are working in alternating shifts. However, the number of people working alternating shifts in social, communication, leisure, transportation, medical services and in factories is probably rapidly rising.
Several headline catastrophes such as the Challenger explosion, the Bhopal disaster, the Exxon Valdez oil spill, the Three Mile Island and the Chernobyl reactor meltdown have been, at least in part, attributed to human errors secondary to fatigue and sleepiness, which might have been related to the effects of shiftwork.
Exposure to shiftwork is associated with increased sick leave and increased prevalence of various somatic conditions, including coronary heart disease and peptic ulcer. Disruption of the circadian rhythm leads to hormonal changes; therefore, women working night shifts are more prone to developing menstrual irregularities, infertility and adverse pregnancy outcomes.
Sleep disorders are not restricted to night hours but they have a profound effect on our everyday daytime functioning, productivity, home, travel and workplace safety, mental and physical wellbeing and QoL. This review only covered the most common sleep disorders (i.e., insomnia, RLS, OSAS and shiftwork-related sleep disorder), but we must acknowledge that there is a large variety of less common sleep disorders that also have deleterious effects on the overall wellbeing and QoL of the individuals affected.
Shiftwork can be defined as “a way of organizing daily working hours in which different persons or teams work in succession to cover more than the usual 8-h workday, up to and including the whole 24 h”. In practical terms, any work schedule is considered shiftwork if they are not within the 09:00-17:00 or 08:00-16:00 time range.