Abstract
The discrepancy between natural sleep-wake rhythm and actual sleep times in shift workers can cause sleep loss and negative daytime consequences. Irregular shift schedules do not follow a fixed structure and change frequently, which makes them particularly harmful and makes affected individuals more susceptible to insomnia. The present study compares insomnia symptoms of non-shift workers, regular shift workers, and irregular shift workers and takes into account the moderating role of the Big Five personality traits and levels of perfectionism. Employees of an Austrian railway company completed an online survey assessing shift schedules, sleep quality and duration, daytime sleepiness, and personality traits. A total of 305 participants, of whom 111 were non-shift workers, 60 regular shift workers, and 134 irregular shift workers, made up the final sample. Irregular shift workers achieved significantly worse scores than one or both of the other groups in time in bed, total sleep time, sleep efficiency, sleep duration, sleep quality, sleep latency, and the number of awakenings. However, the values of the irregular shifts workers are still in the average range and do not indicate clinical insomnia. Participants working regular shifts reported the best sleep quality and longest sleep duration and showed the least nocturnal awakenings, possibly due to higher conscientiousness- and lower neuroticism scores in this group. Agreeableness increased the effect of work schedule on total sleep time while decreasing its effect on the amount of sleep medication taken. Perfectionism increased the effect of work schedule on time in bed and total sleep time. Generalization of results is limited due to the high percentage of males in the sample and using self-report measures only.
Highlights
Shift work, or work performed during non-traditional working hours, leads to a discrepancy between natural sleep-wake rhythm and actual sleep times
Perfectionism was lower in irregular shift workers, as compared to non-shift workers
Irregular shift workers slept less, worse, needed longer to fall asleep, and woke up more often during the night. This is in line with former findings indicating that sleep complaints are more common in irregular shifts (Härmä et al, 2002), and have been suggested to be even more common than in case of permanent night shifts (Pilcher et al, 2000). Even if these results indicate a decrease in sleep quality with increasing shift irregularity, it is not possible to speak of clinical insomnia in this case, since the values of the irregular shift workers are in average range, with sleep efficiency >86%, sleep latency
Summary
Work performed during non-traditional working hours, leads to a discrepancy between natural sleep-wake rhythm and actual sleep times This disruption of the circadian rhythm is likely to cause insomnia and excessive daytime sleepiness (Harrington, 2001; Caruso, 2013; d’Ettorre et al, 2020; Khan et al, 2020; Wen et al, 2020), the main symptoms of shift work sleep disorder (American Academy of Sleep Medicine, 2014). Because arousal levels tend to be higher due to stress and irregular sleep schedules, there are more frequent nighttime awakenings, possibly leading to increased dream recall (Schredl and Reinhard, 2008)
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